Documentation Index

Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt Use this file to discover all available pages before exploring further.

Agent SDK reference - TypeScript

Complete API reference for the TypeScript Agent SDK, including all functions, types, and interfaces.

Installation

npm install @anthropic-ai/claude-agent-sdk

Compile to a single executable

When you compile your application into a single-file executable with bun build --compile, the SDK cannot resolve the bundled CLI binary at runtime. require.resolve does not work inside the compiled executable's $bunfs virtual filesystem, so the SDK throws Native CLI binary for <platform> not found.

To work around this, embed the platform binary as a file asset, extract it to a real path at startup with extractFromBunfs(), and pass that path to pathToClaudeCodeExecutable.

The extractFromBunfs() helper requires @anthropic-ai/claude-agent-sdk v0.3.144 or later. The example below builds for macOS on Apple Silicon:

import binPath from "@anthropic-ai/claude-agent-sdk-darwin-arm64/claude" with { type: "file" };
import { extractFromBunfs } from "@anthropic-ai/claude-agent-sdk/extract";
import { query } from "@anthropic-ai/claude-agent-sdk";

const cliPath = extractFromBunfs(binPath);

for await (const message of query({
  prompt: "Hello",
  options: { pathToClaudeCodeExecutable: cliPath },
})) {
  console.log(message);
}

extractFromBunfs() copies the embedded binary out of the compiled executable's virtual filesystem to a per-user temp directory and returns the real path. Outside a compiled executable it returns the input path unchanged, so the same code runs in development without modification.

Each compiled executable embeds a single platform's binary. Match the platform package in the import to your --target:

• To cross-compile, install the non-matching platform package, for example npm install @anthropic-ai/claude-agent-sdk-linux-x64 --force.
• On Windows, the binary subpath is claude.exe, for example @anthropic-ai/claude-agent-sdk-win32-x64/claude.exe.

Functions

query()

The primary function for interacting with Claude Code. Creates an async generator that streams messages as they arrive.

function query({
  prompt,
  options
}: {
  prompt: string | AsyncIterable<SDKUserMessage>;
  options?: Options;
}): Query;

Parameters

Returns

Returns a Query object that extends AsyncGenerator<SDKMessage, void> with additional methods.

startup()

Pre-warms the CLI subprocess by spawning it and completing the initialize handshake before a prompt is available. The returned WarmQuery handle accepts a prompt later and writes it to an already-ready process, so the first query() call resolves without paying subprocess spawn and initialization cost inline.

function startup(params?: {
  options?: Options;
  initializeTimeoutMs?: number;
}): Promise<WarmQuery>;

Parameters

Returns

Returns a Promise<WarmQuery> that resolves once the subprocess has spawned and completed its initialize handshake.

Example

Call startup() early, for example on application boot, then call .query() on the returned handle once a prompt is ready. This moves subprocess spawn and initialization out of the critical path.

import { startup } from "@anthropic-ai/claude-agent-sdk";

// Pay startup cost upfront
const warm = await startup({ options: { maxTurns: 3 } });

// Later, when a prompt is ready, this is immediate
for await (const message of warm.query("What files are here?")) {
  console.log(message);
}

tool()

Creates a type-safe MCP tool definition for use with SDK MCP servers.

function tool<Schema extends AnyZodRawShape>(
  name: string,
  description: string,
  inputSchema: Schema,
  handler: (args: InferShape<Schema>, extra: unknown) => Promise<CallToolResult>,
  extras?: { annotations?: ToolAnnotations }
): SdkMcpToolDefinition<Schema>;

Parameters

ToolAnnotations

Re-exported from @modelcontextprotocol/sdk/types.js. All fields are optional hints; clients should not rely on them for security decisions.

import { tool } from "@anthropic-ai/claude-agent-sdk";
import { z } from "zod";

const searchTool = tool(
  "search",
  "Search the web",
  { query: z.string() },
  async ({ query }) => {
    return { content: [{ type: "text", text: `Results for: ${query}` }] };
  },
  { annotations: { readOnlyHint: true, openWorldHint: true } }
);

createSdkMcpServer()

Creates an MCP server instance that runs in the same process as your application.

function createSdkMcpServer(options: {
  name: string;
  version?: string;
  tools?: Array<SdkMcpToolDefinition<any>>;
}): McpSdkServerConfigWithInstance;

Parameters

listSessions()

Discovers and lists past sessions with light metadata. Filter by project directory or list sessions across all projects.

function listSessions(options?: ListSessionsOptions): Promise<SDKSessionInfo[]>;

Parameters

Return type: SDKSessionInfo

Example

Print the 10 most recent sessions for a project. Results are sorted by lastModified descending, so the first item is the newest. Omit dir to search across all projects.

import { listSessions } from "@anthropic-ai/claude-agent-sdk";

const sessions = await listSessions({ dir: "/path/to/project", limit: 10 });

for (const session of sessions) {
  console.log(`${session.summary} (${session.sessionId})`);
}

getSessionMessages()

Reads user and assistant messages from a past session transcript.

function getSessionMessages(
  sessionId: string,
  options?: GetSessionMessagesOptions
): Promise<SessionMessage[]>;

Parameters

Return type: SessionMessage

Example

import { listSessions, getSessionMessages } from "@anthropic-ai/claude-agent-sdk";

const [latest] = await listSessions({ dir: "/path/to/project", limit: 1 });

if (latest) {
  const messages = await getSessionMessages(latest.sessionId, {
    dir: "/path/to/project",
    limit: 20
  });

  for (const msg of messages) {
    console.log(`[${msg.type}] ${msg.uuid}`);
  }
}

getSessionInfo()

Reads metadata for a single session by ID without scanning the full project directory.

function getSessionInfo(
  sessionId: string,
  options?: GetSessionInfoOptions
): Promise<SDKSessionInfo | undefined>;

Parameters

Returns SDKSessionInfo, or undefined if the session is not found.

renameSession()

Renames a session by appending a custom-title entry. Repeated calls are safe; the most recent title wins.

function renameSession(
  sessionId: string,
  title: string,
  options?: SessionMutationOptions
): Promise<void>;

Parameters

tagSession()

Tags a session. Pass null to clear the tag. Repeated calls are safe; the most recent tag wins.

function tagSession(
  sessionId: string,
  tag: string | null,
  options?: SessionMutationOptions
): Promise<void>;

Parameters

resolveSettings()

Resolves the effective Claude Code settings for a given directory using the same merge engine as the CLI, without spawning the Claude CLI. Use it to inspect what configuration a query() call would see before invoking one.

function resolveSettings(
  options?: ResolveSettingsOptions
): Promise<ResolvedSettings>;

Parameters

resolveSettings() accepts a single options object. All fields are optional.

Return type: ResolvedSettings

resolveSettings() returns an object describing the merged settings and the source that contributed each key.

Example

The example below resolves settings for a project directory and prints the source that controls the cleanup period.

import { resolveSettings } from "@anthropic-ai/claude-agent-sdk";

const { effective, provenance } = await resolveSettings({
  cwd: "/path/to/project",
  settingSources: ["user", "project", "local"],
});

console.log(`Cleanup period: ${effective.cleanupPeriodDays} days`);
console.log(`Set by: ${provenance.cleanupPeriodDays?.source}`);

Types

Options

Configuration object for the query() function.

Handle slow or stalled API responses

The CLI subprocess reads several environment variables that control API timeouts and stall detection. Pass them through the env option:

const result = query({
  prompt: "Analyze this code",
  options: {
    env: {
      ...process.env,
      API_TIMEOUT_MS: "120000",
      CLAUDE_CODE_MAX_RETRIES: "2",
      CLAUDE_ASYNC_AGENT_STALL_TIMEOUT_MS: "120000",
    },
  },
});

• API_TIMEOUT_MS: per-request timeout on the Anthropic client, in milliseconds. Default 600000. Applies to the main loop and all subagents.
• CLAUDE_CODE_MAX_RETRIES: maximum API retries. Default 10. Each retry gets its own API_TIMEOUT_MS window, so worst-case wall time is roughly API_TIMEOUT_MS × (CLAUDE_CODE_MAX_RETRIES + 1) plus backoff.
• CLAUDE_ASYNC_AGENT_STALL_TIMEOUT_MS: stall watchdog for subagents launched with run_in_background. Default 600000. Resets on each stream event; on stall it aborts the subagent, marks the task failed, and surfaces the error to the parent with any partial result. Does not apply to synchronous subagents.
• CLAUDE_ENABLE_STREAM_WATCHDOG=1 with CLAUDE_STREAM_IDLE_TIMEOUT_MS: aborts the request when headers have arrived but the response body stops streaming. Off by default. CLAUDE_STREAM_IDLE_TIMEOUT_MS defaults to 300000 and is clamped to that minimum. The aborted request goes through the normal retry path.

Query object

Interface returned by the query() function.

interface Query extends AsyncGenerator<SDKMessage, void> {
  interrupt(): Promise<void>;
  rewindFiles(
    userMessageId: string,
    options?: { dryRun?: boolean }
  ): Promise<RewindFilesResult>;
  setPermissionMode(mode: PermissionMode): Promise<void>;
  setModel(model?: string): Promise<void>;
  setMaxThinkingTokens(maxThinkingTokens: number | null): Promise<void>;
  applyFlagSettings(settings: { [K in keyof Settings]?: Settings[K] | null }): Promise<void>;
  initializationResult(): Promise<SDKControlInitializeResponse>;
  supportedCommands(): Promise<SlashCommand[]>;
  supportedModels(): Promise<ModelInfo[]>;
  supportedAgents(): Promise<AgentInfo[]>;
  mcpServerStatus(): Promise<McpServerStatus[]>;
  accountInfo(): Promise<AccountInfo>;
  reconnectMcpServer(serverName: string): Promise<void>;
  toggleMcpServer(serverName: string, enabled: boolean): Promise<void>;
  setMcpServers(servers: Record<string, McpServerConfig>): Promise<McpSetServersResult>;
  streamInput(stream: AsyncIterable<SDKUserMessage>): Promise<void>;
  stopTask(taskId: string): Promise<void>;
  close(): void;
}

Methods

applyFlagSettings()

Changes any setting on a running session without restarting the query. Use it when a setting that has no dedicated setter needs to change mid-session, such as tightening permissions after the agent reads untrusted input. setModel() and setPermissionMode() are dedicated setters for those two keys; applyFlagSettings() is the general form that accepts any subset of the settings keys, and passing model here behaves the same as setModel().

The values are written to the flag-settings layer, the same layer the inline settings option of query() populates at startup. Flag settings sit near the top of the settings precedence order: they override user, project, and local settings, and only managed policy settings can override them. This is the same tier the on-page precedence section calls programmatic options.

Successive calls shallow-merge top-level keys. A second call with { permissions: {...} } replaces the entire permissions object from the prior call rather than deep-merging into it. To clear a key from the flag layer and fall back to lower-precedence sources, pass null for that key. Passing undefined has no effect because JSON serialization drops it.

Only available in streaming input mode, the same constraint as setModel() and setPermissionMode().

The example below switches the active model mid-session, then clears the override so the model falls back to whatever the user or project settings specify.

const q = query({ prompt: messageStream });

// Override the model for the rest of the session
await q.applyFlagSettings({ model: "claude-opus-4-6" });

// Later: clear the override and fall back to lower-precedence settings
await q.applyFlagSettings({ model: null });

WarmQuery

Handle returned by startup(). The subprocess is already spawned and initialized, so calling query() on this handle writes the prompt directly to a ready process with no startup latency.

interface WarmQuery extends AsyncDisposable {
  query(prompt: string | AsyncIterable<SDKUserMessage>): Query;
  close(): void;
}

Methods

WarmQuery implements AsyncDisposable, so it can be used with await using for automatic cleanup.

SDKControlInitializeResponse

Return type of initializationResult(). Contains session initialization data.

type SDKControlInitializeResponse = {
  commands: SlashCommand[];
  agents: AgentInfo[];
  output_style: string;
  available_output_styles: string[];
  models: ModelInfo[];
  account: AccountInfo;
  fast_mode_state?: "off" | "cooldown" | "on";
};

AgentDefinition

Configuration for a subagent defined programmatically.

type AgentDefinition = {
  description: string;
  tools?: string[];
  disallowedTools?: string[];
  prompt: string;
  model?: string;
  mcpServers?: AgentMcpServerSpec[];
  skills?: string[];
  initialPrompt?: string;
  maxTurns?: number;
  background?: boolean;
  memory?: "user" | "project" | "local";
  effort?: "low" | "medium" | "high" | "xhigh" | "max" | number;
  permissionMode?: PermissionMode;
  criticalSystemReminder_EXPERIMENTAL?: string;
};

AgentMcpServerSpec

Specifies MCP servers available to a subagent. Can be a server name (string referencing a server from the parent's mcpServers config) or an inline server configuration record mapping server names to configs.

type AgentMcpServerSpec = string | Record<string, McpServerConfigForProcessTransport>;

Where McpServerConfigForProcessTransport is McpStdioServerConfig | McpSSEServerConfig | McpHttpServerConfig | McpSdkServerConfig.

SettingSource

Controls which filesystem-based configuration sources the SDK loads settings from.

type SettingSource = "user" | "project" | "local";

Default behavior

When settingSources is omitted or undefined, query() loads the same filesystem settings as the Claude Code CLI: user, project, and local. Managed policy settings are loaded in all cases. See What settingSources does not control for inputs that are read regardless of this option, and how to disable them.

Why use settingSources

Disable filesystem settings:

// Do not load user, project, or local settings from disk
const result = query({
  prompt: "Analyze this code",
  options: { settingSources: [] }
});

Load all filesystem settings explicitly:

const result = query({
  prompt: "Analyze this code",
  options: {
    settingSources: ["user", "project", "local"] // Load all settings
  }
});

Load only specific setting sources:

// Load only project settings, ignore user and local
const result = query({
  prompt: "Run CI checks",
  options: {
    settingSources: ["project"] // Only .claude/settings.json
  }
});

Testing and CI environments:

// Ensure consistent behavior in CI by excluding local settings
const result = query({
  prompt: "Run tests",
  options: {
    settingSources: ["project"], // Only team-shared settings
    permissionMode: "bypassPermissions"
  }
});

SDK-only applications:

// Define everything programmatically.
// Pass [] to opt out of filesystem setting sources.
const result = query({
  prompt: "Review this PR",
  options: {
    settingSources: [],
    agents: {
      /* ... */
    },
    mcpServers: {
      /* ... */
    },
    allowedTools: ["Read", "Grep", "Glob"]
  }
});

Loading CLAUDE.md project instructions:

// Load project settings to include CLAUDE.md files
const result = query({
  prompt: "Add a new feature following project conventions",
  options: {
    systemPrompt: {
      type: "preset",
      preset: "claude_code" // Use Claude Code's system prompt
    },
    settingSources: ["project"], // Loads CLAUDE.md from project directory
    allowedTools: ["Read", "Write", "Edit"]
  }
});

Settings precedence

When multiple sources are loaded, settings are merged with this precedence (highest to lowest):

1. Local settings (.claude/settings.local.json)
2. Project settings (.claude/settings.json)
3. User settings (~/.claude/settings.json)

Programmatic options such as agents, allowedTools, and settings override user, project, and local filesystem settings. Managed policy settings take precedence over programmatic options.

PermissionMode

type PermissionMode =
  | "default" // Standard permission behavior
  | "acceptEdits" // Auto-accept file edits
  | "bypassPermissions" // Bypass all permission checks
  | "plan" // Planning mode - read-only tools only
  | "dontAsk" // Don't prompt for permissions, deny if not pre-approved
  | "auto"; // Use a model classifier to approve or deny each tool call

CanUseTool

Custom permission function type for controlling tool usage.

type CanUseTool = (
  toolName: string,
  input: Record<string, unknown>,
  options: {
    signal: AbortSignal;
    suggestions?: PermissionUpdate[];
    blockedPath?: string;
    decisionReason?: string;
    toolUseID: string;
    agentID?: string;
  }
) => Promise<PermissionResult>;

PermissionResult

Result of a permission check.

type PermissionResult =
  | {
      behavior: "allow";
      updatedInput?: Record<string, unknown>;
      updatedPermissions?: PermissionUpdate[];
      toolUseID?: string;
    }
  | {
      behavior: "deny";
      message: string;
      interrupt?: boolean;
      toolUseID?: string;
    };

ToolConfig

Configuration for built-in tool behavior.

type ToolConfig = {
  askUserQuestion?: {
    previewFormat?: "markdown" | "html";
  };
};

McpServerConfig

Configuration for MCP servers.

type McpServerConfig =
  | McpStdioServerConfig
  | McpSSEServerConfig
  | McpHttpServerConfig
  | McpSdkServerConfigWithInstance;

McpStdioServerConfig

type McpStdioServerConfig = {
  type?: "stdio";
  command: string;
  args?: string[];
  env?: Record<string, string>;
};

McpSSEServerConfig

type McpSSEServerConfig = {
  type: "sse";
  url: string;
  headers?: Record<string, string>;
};

McpHttpServerConfig

type McpHttpServerConfig = {
  type: "http";
  url: string;
  headers?: Record<string, string>;
};

McpSdkServerConfigWithInstance

type McpSdkServerConfigWithInstance = {
  type: "sdk";
  name: string;
  instance: McpServer;
};

McpClaudeAIProxyServerConfig

type McpClaudeAIProxyServerConfig = {
  type: "claudeai-proxy";
  url: string;
  id: string;
};

SdkPluginConfig

Configuration for loading plugins in the SDK.

type SdkPluginConfig = {
  type: "local";
  path: string;
};

Example:

plugins: [
  { type: "local", path: "./my-plugin" },
  { type: "local", path: "/absolute/path/to/plugin" }
];

For complete information on creating and using plugins, see Plugins.

Message Types

SDKMessage

Union type of all possible messages returned by the query.

type SDKMessage =
  | SDKAssistantMessage
  | SDKUserMessage
  | SDKUserMessageReplay
  | SDKResultMessage
  | SDKSystemMessage
  | SDKPartialAssistantMessage
  | SDKCompactBoundaryMessage
  | SDKStatusMessage
  | SDKLocalCommandOutputMessage
  | SDKHookStartedMessage
  | SDKHookProgressMessage
  | SDKHookResponseMessage
  | SDKPluginInstallMessage
  | SDKToolProgressMessage
  | SDKAuthStatusMessage
  | SDKTaskNotificationMessage
  | SDKTaskStartedMessage
  | SDKTaskProgressMessage
  | SDKTaskUpdatedMessage
  | SDKSessionStateChangedMessage
  | SDKNotificationMessage
  | SDKFilesPersistedEvent
  | SDKToolUseSummaryMessage
  | SDKMemoryRecallMessage
  | SDKRateLimitEvent
  | SDKElicitationCompleteMessage
  | SDKPermissionDeniedMessage
  | SDKPromptSuggestionMessage
  | SDKAPIRetryMessage
  | SDKMirrorErrorMessage;

SDKAssistantMessage

Assistant response message.

type SDKAssistantMessage = {
  type: "assistant";
  uuid: UUID;
  session_id: string;
  message: BetaMessage; // From Anthropic SDK
  parent_tool_use_id: string | null;
  error?: SDKAssistantMessageError;
};

The message field is a BetaMessage from the Anthropic SDK. It includes fields like id, content, model, stop_reason, and usage.

SDKAssistantMessageError is one of: 'authentication_failed', 'oauth_org_not_allowed', 'billing_error', 'rate_limit', 'invalid_request', 'model_not_found', 'server_error', 'max_output_tokens', or 'unknown'. 'model_not_found' means the selected model doesn't exist or isn't available to your account or deployment.

SDKUserMessage

User input message.

type SDKUserMessage = {
  type: "user";
  uuid?: UUID;
  session_id?: string;
  message: MessageParam; // From Anthropic SDK
  parent_tool_use_id: string | null;
  isSynthetic?: boolean;
  shouldQuery?: boolean;
  tool_use_result?: unknown;
  origin?: SDKMessageOrigin;
};

Set shouldQuery to false to append the message to the transcript without triggering an assistant turn. The message is held and merged into the next user message that does trigger a turn. Use this to inject context, such as the output of a command you ran out of band, without spending a model call on it.

SDKUserMessageReplay

Replayed user message with required UUID.

type SDKUserMessageReplay = {
  type: "user";
  uuid: UUID;
  session_id: string;
  message: MessageParam;
  parent_tool_use_id: string | null;
  isSynthetic?: boolean;
  tool_use_result?: unknown;
  origin?: SDKMessageOrigin;
  isReplay: true;
};

SDKResultMessage

Final result message.

type SDKResultMessage =
  | {
      type: "result";
      subtype: "success";
      uuid: UUID;
      session_id: string;
      duration_ms: number;
      duration_api_ms: number;
      is_error: boolean;
      api_error_status?: number | null;
      num_turns: number;
      result: string;
      stop_reason: string | null;
      ttft_ms?: number;
      total_cost_usd: number;
      usage: NonNullableUsage;
      modelUsage: { [modelName: string]: ModelUsage };
      permission_denials: SDKPermissionDenial[];
      structured_output?: unknown;
      deferred_tool_use?: { id: string; name: string; input: Record<string, unknown> };
      terminal_reason?: TerminalReason;
      fast_mode_state?: FastModeState;
      origin?: SDKMessageOrigin;
    }
  | {
      type: "result";
      subtype:
        | "error_max_turns"
        | "error_during_execution"
        | "error_max_budget_usd"
        | "error_max_structured_output_retries";
      uuid: UUID;
      session_id: string;
      duration_ms: number;
      duration_api_ms: number;
      is_error: boolean;
      num_turns: number;
      stop_reason: string | null;
      total_cost_usd: number;
      usage: NonNullableUsage;
      modelUsage: { [modelName: string]: ModelUsage };
      permission_denials: SDKPermissionDenial[];
      errors: string[];
      terminal_reason?: TerminalReason;
      fast_mode_state?: FastModeState;
      origin?: SDKMessageOrigin;
    };

Several fields on the result carry diagnostic detail beyond subtype:

• api_error_status: the HTTP status code of the API error that terminated the conversation. Absent or null when the turn ended without an API error.
• ttft_ms: time to first token in milliseconds. Present on the success arm only.
• terminal_reason: why the loop ended. One of "completed", "max_turns", "tool_deferred", "aborted_streaming", "aborted_tools", "hook_stopped", "stop_hook_prevented", "blocking_limit", "rapid_refill_breaker", "prompt_too_long", "image_error", or "model_error".
• fast_mode_state: one of "on", "off", or "cooldown".

The origin field forwards the SDKMessageOrigin of the user message that triggered this result. When a background task finishes and the SDK injects a synthetic follow-up turn, the resulting SDKResultMessage carries origin: { kind: "task-notification" }. Check this field to distinguish results that answer your prompt from results emitted for background-task follow-ups, so you can route or suppress the latter. The field is absent for results emitted before any user turn, such as startup errors.

When a PreToolUse hook returns permissionDecision: "defer", the result has stop_reason: "tool_deferred" and deferred_tool_use carries the pending tool's id, name, and input. Read this field to surface the request in your own UI, then resume with the same session_id to continue. See Defer a tool call for later for the full round trip.

SDKSystemMessage

System initialization message.

type SDKSystemMessage = {
  type: "system";
  subtype: "init";
  uuid: UUID;
  session_id: string;
  agents?: string[];
  apiKeySource: ApiKeySource;
  betas?: string[];
  claude_code_version: string;
  cwd: string;
  tools: string[];
  mcp_servers: {
    name: string;
    status: string;
  }[];
  model: string;
  permissionMode: PermissionMode;
  slash_commands: string[];
  output_style: string;
  skills: string[];
  plugins: { name: string; path: string }[];
};

SDKPartialAssistantMessage

Streaming partial message (only when includePartialMessages is true).

type SDKPartialAssistantMessage = {
  type: "stream_event";
  event: BetaRawMessageStreamEvent; // From Anthropic SDK
  parent_tool_use_id: string | null;
  uuid: UUID;
  session_id: string;
};

SDKCompactBoundaryMessage

Message indicating a conversation compaction boundary.

type SDKCompactBoundaryMessage = {
  type: "system";
  subtype: "compact_boundary";
  uuid: UUID;
  session_id: string;
  compact_metadata: {
    trigger: "manual" | "auto";
    pre_tokens: number;
  };
};

SDKPluginInstallMessage

Plugin installation progress event. Emitted when CLAUDE_CODE_SYNC_PLUGIN_INSTALL is set, so your Agent SDK application can track marketplace plugin installation before the first turn. The started and completed statuses bracket the overall install. The installed and failed statuses report individual marketplaces and include name.

type SDKPluginInstallMessage = {
  type: "system";
  subtype: "plugin_install";
  status: "started" | "installed" | "failed" | "completed";
  name?: string;
  error?: string;
  uuid: UUID;
  session_id: string;
};

SDKPermissionDeniedMessage

Stream event emitted when the permission system auto-denies a tool call without an interactive prompt. Use it to render the denial in your UI as it happens, rather than only observing the is_error tool result that follows. The interactive ask path reaches your application separately through the canUseTool callback. Denials issued by a PreToolUse hook are not reported through this event.

This event requires Claude Code v2.1.136 or later.

type SDKPermissionDeniedMessage = {
  type: "system";
  subtype: "permission_denied";
  tool_name: string;
  tool_use_id: string;
  agent_id?: string;
  decision_reason_type?: string;
  decision_reason?: string;
  message: string;
  uuid: UUID;
  session_id: string;
};

SDKPermissionDenial

Information about a denied tool use.

type SDKPermissionDenial = {
  tool_name: string;
  tool_use_id: string;
  tool_input: Record<string, unknown>;
};

SDKMessageOrigin

Provenance of a user-role message. This appears as origin on SDKUserMessage and is forwarded onto the corresponding SDKResultMessage so you can tell what triggered a given turn.

type SDKMessageOrigin =
  | { kind: "human" }
  | { kind: "channel"; server: string }
  | { kind: "peer"; from: string; name?: string }
  | { kind: "task-notification" }
  | { kind: "coordinator" };

Hook Types

For a comprehensive guide on using hooks with examples and common patterns, see the Hooks guide.

HookEvent

Available hook events.

type HookEvent =
  | "PreToolUse"
  | "PostToolUse"
  | "PostToolUseFailure"
  | "PostToolBatch"
  | "Notification"
  | "UserPromptSubmit"
  | "SessionStart"
  | "SessionEnd"
  | "Stop"
  | "SubagentStart"
  | "SubagentStop"
  | "PreCompact"
  | "PermissionRequest"
  | "Setup"
  | "TeammateIdle"
  | "TaskCompleted"
  | "ConfigChange"
  | "WorktreeCreate"
  | "WorktreeRemove";

HookCallback

Hook callback function type.

type HookCallback = (
  input: HookInput, // Union of all hook input types
  toolUseID: string | undefined,
  options: { signal: AbortSignal }
) => Promise<HookJSONOutput>;

HookCallbackMatcher

Hook configuration with optional matcher.

interface HookCallbackMatcher {
  matcher?: string;
  hooks: HookCallback[];
  timeout?: number; // Timeout in seconds for all hooks in this matcher
}

HookInput

Union type of all hook input types.

type HookInput =
  | PreToolUseHookInput
  | PostToolUseHookInput
  | PostToolUseFailureHookInput
  | PostToolBatchHookInput
  | NotificationHookInput
  | UserPromptSubmitHookInput
  | SessionStartHookInput
  | SessionEndHookInput
  | StopHookInput
  | SubagentStartHookInput
  | SubagentStopHookInput
  | PreCompactHookInput
  | PermissionRequestHookInput
  | SetupHookInput
  | TeammateIdleHookInput
  | TaskCompletedHookInput
  | ConfigChangeHookInput
  | WorktreeCreateHookInput
  | WorktreeRemoveHookInput;

BaseHookInput

Base interface that all hook input types extend.

type BaseHookInput = {
  session_id: string;
  transcript_path: string;
  cwd: string;
  permission_mode?: string;
  effort?: { level: string };
  agent_id?: string;
  agent_type?: string;
};

PreToolUseHookInput

type PreToolUseHookInput = BaseHookInput & {
  hook_event_name: "PreToolUse";
  tool_name: string;
  tool_input: unknown;
  tool_use_id: string;
};

PostToolUseHookInput

type PostToolUseHookInput = BaseHookInput & {
  hook_event_name: "PostToolUse";
  tool_name: string;
  tool_input: unknown;
  tool_response: unknown;
  tool_use_id: string;
  duration_ms?: number;
};

PostToolUseFailureHookInput

type PostToolUseFailureHookInput = BaseHookInput & {
  hook_event_name: "PostToolUseFailure";
  tool_name: string;
  tool_input: unknown;
  tool_use_id: string;
  error: string;
  is_interrupt?: boolean;
  duration_ms?: number;
};

PostToolBatchHookInput

Fires once after every tool call in a batch has resolved, before the next model request. tool_response carries the serialized tool_result content the model sees; the shape differs from PostToolUseHookInput's structured Output object.

type PostToolBatchHookInput = BaseHookInput & {
  hook_event_name: "PostToolBatch";
  tool_calls: PostToolBatchToolCall[];
};

type PostToolBatchToolCall = {
  tool_name: string;
  tool_input: unknown;
  tool_use_id: string;
  tool_response?: unknown;
};

NotificationHookInput

type NotificationHookInput = BaseHookInput & {
  hook_event_name: "Notification";
  message: string;
  title?: string;
  notification_type: string;
};

UserPromptSubmitHookInput

type UserPromptSubmitHookInput = BaseHookInput & {
  hook_event_name: "UserPromptSubmit";
  prompt: string;
};

SessionStartHookInput

type SessionStartHookInput = BaseHookInput & {
  hook_event_name: "SessionStart";
  source: "startup" | "resume" | "clear" | "compact";
  agent_type?: string;
  model?: string;
};

SessionEndHookInput

type SessionEndHookInput = BaseHookInput & {
  hook_event_name: "SessionEnd";
  reason: ExitReason; // String from EXIT_REASONS array
};

StopHookInput

type StopHookInput = BaseHookInput & {
  hook_event_name: "Stop";
  stop_hook_active: boolean;
  last_assistant_message?: string;
  background_tasks?: BackgroundTaskSummary[];
  session_crons?: SessionCronSummary[];
};

SubagentStartHookInput

type SubagentStartHookInput = BaseHookInput & {
  hook_event_name: "SubagentStart";
  agent_id: string;
  agent_type: string;
};

SubagentStopHookInput

type SubagentStopHookInput = BaseHookInput & {
  hook_event_name: "SubagentStop";
  stop_hook_active: boolean;
  agent_id: string;
  agent_transcript_path: string;
  agent_type: string;
  last_assistant_message?: string;
  background_tasks?: BackgroundTaskSummary[];
  session_crons?: SessionCronSummary[];
};

type BackgroundTaskSummary = {
  id: string;
  type: string;
  status: string;
  description: string;
  command?: string;
  agent_type?: string;
  server?: string;
  tool?: string;
  name?: string;
};

type SessionCronSummary = {
  id: string;
  schedule: string;
  recurring: boolean;
  prompt: string;
};

PreCompactHookInput

type PreCompactHookInput = BaseHookInput & {
  hook_event_name: "PreCompact";
  trigger: "manual" | "auto";
  custom_instructions: string | null;
};

PermissionRequestHookInput

type PermissionRequestHookInput = BaseHookInput & {
  hook_event_name: "PermissionRequest";
  tool_name: string;
  tool_input: unknown;
  permission_suggestions?: PermissionUpdate[];
};

SetupHookInput

type SetupHookInput = BaseHookInput & {
  hook_event_name: "Setup";
  trigger: "init" | "maintenance";
};

TeammateIdleHookInput

type TeammateIdleHookInput = BaseHookInput & {
  hook_event_name: "TeammateIdle";
  teammate_name: string;
  team_name: string;
};

TaskCompletedHookInput

type TaskCompletedHookInput = BaseHookInput & {
  hook_event_name: "TaskCompleted";
  task_id: string;
  task_subject: string;
  task_description?: string;
  teammate_name?: string;
  team_name?: string;
};

ConfigChangeHookInput

type ConfigChangeHookInput = BaseHookInput & {
  hook_event_name: "ConfigChange";
  source:
    | "user_settings"
    | "project_settings"
    | "local_settings"
    | "policy_settings"
    | "skills";
  file_path?: string;
};

WorktreeCreateHookInput

type WorktreeCreateHookInput = BaseHookInput & {
  hook_event_name: "WorktreeCreate";
  name: string;
};

WorktreeRemoveHookInput

type WorktreeRemoveHookInput = BaseHookInput & {
  hook_event_name: "WorktreeRemove";
  worktree_path: string;
};

HookJSONOutput

Hook return value.

type HookJSONOutput = AsyncHookJSONOutput | SyncHookJSONOutput;

AsyncHookJSONOutput

type AsyncHookJSONOutput = {
  async: true;
  asyncTimeout?: number;
};

SyncHookJSONOutput

type SyncHookJSONOutput = {
  continue?: boolean;
  suppressOutput?: boolean;
  stopReason?: string;
  decision?: "approve" | "block";
  systemMessage?: string;
  reason?: string;
  hookSpecificOutput?:
    | {
        hookEventName: "PreToolUse";
        permissionDecision?: "allow" | "deny" | "ask" | "defer";
        permissionDecisionReason?: string;
        updatedInput?: Record<string, unknown>;
        additionalContext?: string;
      }
    | {
        hookEventName: "UserPromptSubmit";
        additionalContext?: string;
      }
    | {
        hookEventName: "SessionStart";
        additionalContext?: string;
      }
    | {
        hookEventName: "Setup";
        additionalContext?: string;
      }
    | {
        hookEventName: "SubagentStart";
        additionalContext?: string;
      }
    | {
        hookEventName: "PostToolUse";
        additionalContext?: string;
        updatedToolOutput?: unknown;
        /** @deprecated Use `updatedToolOutput`, which works for all tools. */
        updatedMCPToolOutput?: unknown;
      }
    | {
        hookEventName: "PostToolUseFailure";
        additionalContext?: string;
      }
    | {
        hookEventName: "PostToolBatch";
        additionalContext?: string;
      }
    | {
        hookEventName: "Notification";
        additionalContext?: string;
      }
    | {
        hookEventName: "PermissionRequest";
        decision:
          | {
              behavior: "allow";
              updatedInput?: Record<string, unknown>;
              updatedPermissions?: PermissionUpdate[];
            }
          | {
              behavior: "deny";
              message?: string;
              interrupt?: boolean;
            };
      };
};

Tool Input Types

Documentation of input schemas for all built-in Claude Code tools. These types are exported from @anthropic-ai/claude-agent-sdk and can be used for type-safe tool interactions.

ToolInputSchemas

Union of all tool input types, exported from @anthropic-ai/claude-agent-sdk.

type ToolInputSchemas =
  | AgentInput
  | AskUserQuestionInput
  | BashInput
  | TaskOutputInput
  | EnterWorktreeInput
  | ExitPlanModeInput
  | FileEditInput
  | FileReadInput
  | FileWriteInput
  | GlobInput
  | GrepInput
  | ListMcpResourcesInput
  | McpInput
  | MonitorInput
  | NotebookEditInput
  | ReadMcpResourceInput
  | SubscribeMcpResourceInput
  | SubscribePollingInput
  | TaskCreateInput
  | TaskGetInput
  | TaskListInput
  | TaskStopInput
  | TaskUpdateInput
  | TodoWriteInput
  | UnsubscribeMcpResourceInput
  | UnsubscribePollingInput
  | WebFetchInput
  | WebSearchInput;

Agent

Tool name: Agent (previously Task, which is still accepted as an alias)

type AgentInput = {
  description: string;
  prompt: string;
  subagent_type: string;
  model?: "sonnet" | "opus" | "haiku";
  resume?: string;
  run_in_background?: boolean;
  max_turns?: number;
  name?: string;
  team_name?: string;
  mode?: "acceptEdits" | "bypassPermissions" | "default" | "dontAsk" | "plan";
  isolation?: "worktree";
};

Launches a new agent to handle complex, multi-step tasks autonomously.

AskUserQuestion

Tool name: AskUserQuestion

type AskUserQuestionInput = {
  questions: Array<{
    question: string;
    header: string;
    options: Array<{ label: string; description: string; preview?: string }>;
    multiSelect: boolean;
  }>;
};

Asks the user clarifying questions during execution. See Handle approvals and user input for usage details.

Bash

Tool name: Bash

type BashInput = {
  command: string;
  timeout?: number;
  description?: string;
  run_in_background?: boolean;
  dangerouslyDisableSandbox?: boolean;
};

Executes bash commands in a persistent shell session with optional timeout and background execution.

Monitor

Tool name: Monitor

type MonitorInput = {
  command: string;
  description: string;
  timeout_ms?: number;
  persistent?: boolean;
};

Runs a background script and delivers each stdout line to Claude as an event so it can react without polling. Set persistent: true for session-length watches such as log tails. Monitor follows the same permission rules as Bash. See the Monitor tool reference for behavior and provider availability.

TaskOutput

Tool name: TaskOutput

type TaskOutputInput = {
  task_id: string;
  block: boolean;
  timeout: number;
};

Retrieves output from a running or completed background task.

Edit

Tool name: Edit

type FileEditInput = {
  file_path: string;
  old_string: string;
  new_string: string;
  replace_all?: boolean;
};

Performs exact string replacements in files.

Read

Tool name: Read

type FileReadInput = {
  file_path: string;
  offset?: number;
  limit?: number;
  pages?: string;
};

Reads files from the local filesystem, including text, images, PDFs, and Jupyter notebooks. Use pages for PDF page ranges (for example, "1-5").

Write

Tool name: Write

type FileWriteInput = {
  file_path: string;
  content: string;
};

Writes a file to the local filesystem, overwriting if it exists.

Glob

Tool name: Glob

type GlobInput = {
  pattern: string;
  path?: string;
};

Fast file pattern matching that works with any codebase size.

Grep

Tool name: Grep

type GrepInput = {
  pattern: string;
  path?: string;
  glob?: string;
  type?: string;
  output_mode?: "content" | "files_with_matches" | "count";
  "-i"?: boolean;
  "-n"?: boolean;
  "-B"?: number;
  "-A"?: number;
  "-C"?: number;
  context?: number;
  head_limit?: number;
  offset?: number;
  multiline?: boolean;
};

Powerful search tool built on ripgrep with regex support.

TaskStop

Tool name: TaskStop

type TaskStopInput = {
  task_id?: string;
  shell_id?: string; // Deprecated: use task_id
};

Stops a running background task or shell by ID.

NotebookEdit

Tool name: NotebookEdit

type NotebookEditInput = {
  notebook_path: string;
  cell_id?: string;
  new_source: string;
  cell_type?: "code" | "markdown";
  edit_mode?: "replace" | "insert" | "delete";
};

Edits cells in Jupyter notebook files.

WebFetch

Tool name: WebFetch

type WebFetchInput = {
  url: string;
  prompt: string;
};

Fetches content from a URL and processes it with an AI model.

WebSearch

Tool name: WebSearch

type WebSearchInput = {
  query: string;
  allowed_domains?: string[];
  blocked_domains?: string[];
};

Searches the web and returns formatted results.

TodoWrite

Tool name: TodoWrite

type TodoWriteInput = {
  todos: Array<{
    content: string;
    status: "pending" | "in_progress" | "completed";
    activeForm: string;
  }>;
};

Creates and manages a structured task list for tracking progress.

TaskCreate

Tool name: TaskCreate

type TaskCreateInput = {
  subject: string;
  description: string;
  activeForm?: string;
  metadata?: Record<string, unknown>;
};

Creates a single task and returns its assigned ID.

TaskUpdate

Tool name: TaskUpdate

type TaskUpdateInput = {
  taskId: string;
  status?: "pending" | "in_progress" | "completed" | "deleted";
  subject?: string;
  description?: string;
  activeForm?: string;
  addBlocks?: string[];
  addBlockedBy?: string[];
  owner?: string;
  metadata?: Record<string, unknown>;
};

Patches one task by ID. Set status to "deleted" to remove it.

TaskGet

Tool name: TaskGet

type TaskGetInput = {
  taskId: string;
};

Returns full details for one task, or null when the ID is not found.

TaskList

Tool name: TaskList

type TaskListInput = {};

Returns a snapshot of all tasks in the current list.

ExitPlanMode

Tool name: ExitPlanMode

type ExitPlanModeInput = {
  allowedPrompts?: Array<{
    tool: "Bash";
    prompt: string;
  }>;
};

Exits planning mode. Optionally specifies prompt-based permissions needed to implement the plan.

ListMcpResources

Tool name: ListMcpResources

type ListMcpResourcesInput = {
  server?: string;
};

Lists available MCP resources from connected servers.

ReadMcpResource

Tool name: ReadMcpResource

type ReadMcpResourceInput = {
  server: string;
  uri: string;
};

Reads a specific MCP resource from a server.

EnterWorktree

Tool name: EnterWorktree

type EnterWorktreeInput = {
  name?: string;
  path?: string;
};

Creates and enters a temporary git worktree for isolated work. Pass path to switch into an existing worktree of the current repository instead of creating a new one. name and path are mutually exclusive.

Tool Output Types

Documentation of output schemas for all built-in Claude Code tools. These types are exported from @anthropic-ai/claude-agent-sdk and represent the actual response data returned by each tool.

ToolOutputSchemas

Union of all tool output types.

type ToolOutputSchemas =
  | AgentOutput
  | AskUserQuestionOutput
  | BashOutput
  | EnterWorktreeOutput
  | ExitPlanModeOutput
  | FileEditOutput
  | FileReadOutput
  | FileWriteOutput
  | GlobOutput
  | GrepOutput
  | ListMcpResourcesOutput
  | MonitorOutput
  | NotebookEditOutput
  | ReadMcpResourceOutput
  | TaskCreateOutput
  | TaskGetOutput
  | TaskListOutput
  | TaskStopOutput
  | TaskUpdateOutput
  | TodoWriteOutput
  | WebFetchOutput
  | WebSearchOutput;

Agent

Tool name: Agent (previously Task, which is still accepted as an alias)

type AgentOutput =
  | {
      status: "completed";
      agentId: string;
      content: Array<{ type: "text"; text: string }>;
      totalToolUseCount: number;
      totalDurationMs: number;
      totalTokens: number;
      usage: {
        input_tokens: number;
        output_tokens: number;
        cache_creation_input_tokens: number | null;
        cache_read_input_tokens: number | null;
        server_tool_use: {
          web_search_requests: number;
          web_fetch_requests: number;
        } | null;
        service_tier: ("standard" | "priority" | "batch") | null;
        cache_creation: {
          ephemeral_1h_input_tokens: number;
          ephemeral_5m_input_tokens: number;
        } | null;
      };
      prompt: string;
    }
  | {
      status: "async_launched";
      agentId: string;
      description: string;
      prompt: string;
      outputFile: string;
      canReadOutputFile?: boolean;
    }
  | {
      status: "sub_agent_entered";
      description: string;
      message: string;
    };

Returns the result from the subagent. Discriminated on the status field: "completed" for finished tasks, "async_launched" for background tasks, and "sub_agent_entered" for interactive subagents.

AskUserQuestion

Tool name: AskUserQuestion

type AskUserQuestionOutput = {
  questions: Array<{
    question: string;
    header: string;
    options: Array<{ label: string; description: string; preview?: string }>;
    multiSelect: boolean;
  }>;
  answers: Record<string, string>;
};

Returns the questions asked and the user's answers.

Bash

Tool name: Bash

type BashOutput = {
  stdout: string;
  stderr: string;
  rawOutputPath?: string;
  interrupted: boolean;
  isImage?: boolean;
  backgroundTaskId?: string;
  backgroundedByUser?: boolean;
  dangerouslyDisableSandbox?: boolean;
  returnCodeInterpretation?: string;
  structuredContent?: unknown[];
  persistedOutputPath?: string;
  persistedOutputSize?: number;
};

Returns command output with stdout/stderr split. Background commands include a backgroundTaskId.

Monitor

Tool name: Monitor

type MonitorOutput = {
  taskId: string;
  timeoutMs: number;
  persistent?: boolean;
};

Returns the background task ID for the running monitor. Use this ID with TaskStop to cancel the watch early.

Edit

Tool name: Edit

type FileEditOutput = {
  filePath: string;
  oldString: string;
  newString: string;
  originalFile: string;
  structuredPatch: Array<{
    oldStart: number;
    oldLines: number;
    newStart: number;
    newLines: number;
    lines: string[];
  }>;
  userModified: boolean;
  replaceAll: boolean;
  gitDiff?: {
    filename: string;
    status: "modified" | "added";
    additions: number;
    deletions: number;
    changes: number;
    patch: string;
  };
};

Returns the structured diff of the edit operation.

Read

Tool name: Read

type FileReadOutput =
  | {
      type: "text";
      file: {
        filePath: string;
        content: string;
        numLines: number;
        startLine: number;
        totalLines: number;
      };
    }
  | {
      type: "image";
      file: {
        base64: string;
        type: "image/jpeg" | "image/png" | "image/gif" | "image/webp";
        originalSize: number;
        dimensions?: {
          originalWidth?: number;
          originalHeight?: number;
          displayWidth?: number;
          displayHeight?: number;
        };
      };
    }
  | {
      type: "notebook";
      file: {
        filePath: string;
        cells: unknown[];
      };
    }
  | {
      type: "pdf";
      file: {
        filePath: string;
        base64: string;
        originalSize: number;
      };
    }
  | {
      type: "parts";
      file: {
        filePath: string;
        originalSize: number;
        count: number;
        outputDir: string;
      };
    };

Returns file contents in a format appropriate to the file type. Discriminated on the type field.

Write

Tool name: Write

type FileWriteOutput = {
  type: "create" | "update";
  filePath: string;
  content: string;
  structuredPatch: Array<{
    oldStart: number;
    oldLines: number;
    newStart: number;
    newLines: number;
    lines: string[];
  }>;
  originalFile: string | null;
  gitDiff?: {
    filename: string;
    status: "modified" | "added";
    additions: number;
    deletions: number;
    changes: number;
    patch: string;
  };
};

Returns the write result with structured diff information.

Glob

Tool name: Glob

type GlobOutput = {
  durationMs: number;
  numFiles: number;
  filenames: string[];
  truncated: boolean;
};

Returns file paths matching the glob pattern, sorted by modification time.

Grep

Tool name: Grep

type GrepOutput = {
  mode?: "content" | "files_with_matches" | "count";
  numFiles: number;
  filenames: string[];
  content?: string;
  numLines?: number;
  numMatches?: number;
  appliedLimit?: number;
  appliedOffset?: number;
};

Returns search results. The shape varies by mode: file list, content with matches, or match counts.

TaskStop

Tool name: TaskStop

type TaskStopOutput = {
  message: string;
  task_id: string;
  task_type: string;
  command?: string;
};

Returns confirmation after stopping the background task.

NotebookEdit

Tool name: NotebookEdit

type NotebookEditOutput = {
  new_source: string;
  cell_id?: string;
  cell_type: "code" | "markdown";
  language: string;
  edit_mode: string;
  error?: string;
  notebook_path: string;
  original_file: string;
  updated_file: string;
};

Returns the result of the notebook edit with original and updated file contents.

WebFetch

Tool name: WebFetch

type WebFetchOutput = {
  bytes: number;
  code: number;
  codeText: string;
  result: string;
  durationMs: number;
  url: string;
};

Returns the fetched content with HTTP status and metadata.

WebSearch

Tool name: WebSearch

type WebSearchOutput = {
  query: string;
  results: Array<
    | {
        tool_use_id: string;
        content: Array<{ title: string; url: string }>;
      }
    | string
  >;
  durationSeconds: number;
};

Returns search results from the web.

TodoWrite

Tool name: TodoWrite

type TodoWriteOutput = {
  oldTodos: Array<{
    content: string;
    status: "pending" | "in_progress" | "completed";
    activeForm: string;
  }>;
  newTodos: Array<{
    content: string;
    status: "pending" | "in_progress" | "completed";
    activeForm: string;
  }>;
};

Returns the previous and updated task lists.

TaskCreate

Tool name: TaskCreate

type TaskCreateOutput = {
  task: {
    id: string;
    subject: string;
  };
};

Returns the created task with its assigned ID.

TaskUpdate

Tool name: TaskUpdate

type TaskUpdateOutput = {
  success: boolean;
  taskId: string;
  updatedFields: string[];
  error?: string;
  statusChange?: {
    from: string;
    to: string;
  };
};

Returns the update result, including which fields changed.

TaskGet

Tool name: TaskGet

type TaskGetOutput = {
  task: {
    id: string;
    subject: string;
    description: string;
    status: "pending" | "in_progress" | "completed";
    blocks: string[];
    blockedBy: string[];
  } | null;
};

Returns the full task record, or null when the ID is not found.

TaskList

Tool name: TaskList

type TaskListOutput = {
  tasks: Array<{
    id: string;
    subject: string;
    status: "pending" | "in_progress" | "completed";
    owner?: string;
    blockedBy: string[];
  }>;
};

Returns a snapshot of all tasks in the current list.

ExitPlanMode

Tool name: ExitPlanMode

type ExitPlanModeOutput = {
  plan: string | null;
  isAgent: boolean;
  filePath?: string;
  hasTaskTool?: boolean;
  awaitingLeaderApproval?: boolean;
  requestId?: string;
};

Returns the plan state after exiting plan mode.

ListMcpResources

Tool name: ListMcpResources

type ListMcpResourcesOutput = Array<{
  uri: string;
  name: string;
  mimeType?: string;
  description?: string;
  server: string;
}>;

Returns an array of available MCP resources.

ReadMcpResource

Tool name: ReadMcpResource

type ReadMcpResourceOutput = {
  contents: Array<{
    uri: string;
    mimeType?: string;
    text?: string;
  }>;
};

Returns the contents of the requested MCP resource.

EnterWorktree

Tool name: EnterWorktree

type EnterWorktreeOutput = {
  worktreePath: string;
  worktreeBranch?: string;
  message: string;
};

Returns information about the git worktree.

Permission Types

PermissionUpdate

Operations for updating permissions.

type PermissionUpdate =
  | {
      type: "addRules";
      rules: PermissionRuleValue[];
      behavior: PermissionBehavior;
      destination: PermissionUpdateDestination;
    }
  | {
      type: "replaceRules";
      rules: PermissionRuleValue[];
      behavior: PermissionBehavior;
      destination: PermissionUpdateDestination;
    }
  | {
      type: "removeRules";
      rules: PermissionRuleValue[];
      behavior: PermissionBehavior;
      destination: PermissionUpdateDestination;
    }
  | {
      type: "setMode";
      mode: PermissionMode;
      destination: PermissionUpdateDestination;
    }
  | {
      type: "addDirectories";
      directories: string[];
      destination: PermissionUpdateDestination;
    }
  | {
      type: "removeDirectories";
      directories: string[];
      destination: PermissionUpdateDestination;
    };

PermissionBehavior

type PermissionBehavior = "allow" | "deny" | "ask";

PermissionUpdateDestination

type PermissionUpdateDestination =
  | "userSettings" // Global user settings
  | "projectSettings" // Per-directory project settings
  | "localSettings" // Gitignored local settings
  | "session" // Current session only
  | "cliArg"; // CLI argument

PermissionRuleValue

type PermissionRuleValue = {
  toolName: string;
  ruleContent?: string;
};

Other Types

ApiKeySource

type ApiKeySource = "user" | "project" | "org" | "temporary" | "oauth";

SdkBeta

Available beta features that can be enabled via the betas option. See Beta headers for more information.

type SdkBeta = "context-1m-2025-08-07";

SlashCommand

Information about an available slash command.

type SlashCommand = {
  name: string;
  description: string;
  argumentHint: string;
  aliases?: string[];
};

ModelInfo

Information about an available model.

type ModelInfo = {
  value: string;
  displayName: string;
  description: string;
  supportsEffort?: boolean;
  supportedEffortLevels?: ("low" | "medium" | "high" | "xhigh" | "max")[];
  supportsAdaptiveThinking?: boolean;
  supportsFastMode?: boolean;
};

AgentInfo

Information about an available subagent that can be invoked via the Agent tool.

type AgentInfo = {
  name: string;
  description: string;
  model?: string;
};

McpServerStatus

Status of a connected MCP server.

type McpServerStatus = {
  name: string;
  status: "connected" | "failed" | "needs-auth" | "pending" | "disabled";
  serverInfo?: {
    name: string;
    version: string;
  };
  error?: string;
  config?: McpServerStatusConfig;
  scope?: string;
  tools?: {
    name: string;
    description?: string;
    annotations?: {
      readOnly?: boolean;
      destructive?: boolean;
      openWorld?: boolean;
    };
  }[];
};

McpServerStatusConfig

The configuration of an MCP server as reported by mcpServerStatus(). This is the union of all MCP server transport types.

type McpServerStatusConfig =
  | McpStdioServerConfig
  | McpSSEServerConfig
  | McpHttpServerConfig
  | McpSdkServerConfig
  | McpClaudeAIProxyServerConfig;

See McpServerConfig for details on each transport type.

AccountInfo

Account information for the authenticated user.

type AccountInfo = {
  email?: string;
  organization?: string;
  subscriptionType?: string;
  tokenSource?: string;
  apiKeySource?: string;
};

ModelUsage

Per-model usage statistics returned in result messages. The costUSD value is a client-side estimate. See Track cost and usage for billing caveats.

type ModelUsage = {
  inputTokens: number;
  outputTokens: number;
  cacheReadInputTokens: number;
  cacheCreationInputTokens: number;
  webSearchRequests: number;
  costUSD: number;
  contextWindow: number;
  maxOutputTokens: number;
};

ConfigScope

type ConfigScope = "local" | "user" | "project";

NonNullableUsage

A version of Usage with all nullable fields made non-nullable.

type NonNullableUsage = {
  [K in keyof Usage]: NonNullable<Usage[K]>;
};

Usage

Token usage statistics. This is the BetaUsage type from @anthropic-ai/sdk.

type Usage = {
  input_tokens: number;
  output_tokens: number;
  cache_creation_input_tokens: number | null;
  cache_read_input_tokens: number | null;
  cache_creation: {
    ephemeral_5m_input_tokens: number;
    ephemeral_1h_input_tokens: number;
  } | null;
  server_tool_use: BetaServerToolUsage | null;
  service_tier: "standard" | "priority" | "batch" | null;
  speed: "standard" | "fast" | null;
  inference_geo: string | null;
  iterations: BetaIterationsUsage | null;
};

BetaServerToolUsage and BetaIterationsUsage are defined in @anthropic-ai/sdk.

CallToolResult

MCP tool result type (from @modelcontextprotocol/sdk/types.js). structuredContent is a JSON object that can be returned alongside content, including image blocks. See Return structured data.

type CallToolResult = {
  content: Array<{
    type: "text" | "image" | "resource";
    // Additional fields vary by type
  }>;
  structuredContent?: Record<string, unknown>;
  isError?: boolean;
};

ThinkingConfig

Controls Claude's thinking/reasoning behavior. Takes precedence over the deprecated maxThinkingTokens.

type ThinkingDisplay = "summarized" | "omitted";

type ThinkingConfig =
  | { type: "adaptive"; display?: ThinkingDisplay } // The model determines when and how much to reason (Opus 4.6+)
  | { type: "enabled"; budgetTokens?: number; display?: ThinkingDisplay } // Fixed thinking token budget
  | { type: "disabled" }; // No extended thinking

The optional display field controls whether thinking text is returned "summarized" or "omitted". On Claude Opus 4.7 and later, the API default is "omitted", so set "summarized" to receive thinking content in thinking blocks.

SpawnedProcess

Interface for custom process spawning (used with spawnClaudeCodeProcess option). ChildProcess already satisfies this interface.

interface SpawnedProcess {
  stdin: Writable;
  stdout: Readable;
  readonly killed: boolean;
  readonly exitCode: number | null;
  kill(signal: NodeJS.Signals): boolean;
  on(
    event: "exit",
    listener: (code: number | null, signal: NodeJS.Signals | null) => void
  ): void;
  on(event: "error", listener: (error: Error) => void): void;
  once(
    event: "exit",
    listener: (code: number | null, signal: NodeJS.Signals | null) => void
  ): void;
  once(event: "error", listener: (error: Error) => void): void;
  off(
    event: "exit",
    listener: (code: number | null, signal: NodeJS.Signals | null) => void
  ): void;
  off(event: "error", listener: (error: Error) => void): void;
}

SpawnOptions

Options passed to the custom spawn function.

interface SpawnOptions {
  command: string;
  args: string[];
  cwd?: string;
  env: Record<string, string | undefined>;
  signal: AbortSignal;
}

McpSetServersResult

Result of a setMcpServers() operation.

type McpSetServersResult = {
  added: string[];
  removed: string[];
  errors: Record<string, string>;
};

RewindFilesResult

Result of a rewindFiles() operation.

type RewindFilesResult = {
  canRewind: boolean;
  error?: string;
  filesChanged?: string[];
  insertions?: number;
  deletions?: number;
};

SDKStatusMessage

Status update message (e.g., compacting).

type SDKStatusMessage = {
  type: "system";
  subtype: "status";
  status: "compacting" | null;
  permissionMode?: PermissionMode;
  uuid: UUID;
  session_id: string;
};

SDKTaskNotificationMessage

Notification when a background task completes, fails, or is stopped. Background tasks include run_in_background Bash commands, Monitor watches, and background subagents.

type SDKTaskNotificationMessage = {
  type: "system";
  subtype: "task_notification";
  task_id: string;
  tool_use_id?: string;
  status: "completed" | "failed" | "stopped";
  output_file: string;
  summary: string;
  usage?: {
    total_tokens: number;
    tool_uses: number;
    duration_ms: number;
  };
  uuid: UUID;
  session_id: string;
};

SDKToolUseSummaryMessage

Summary of tool usage in a conversation.

type SDKToolUseSummaryMessage = {
  type: "tool_use_summary";
  summary: string;
  preceding_tool_use_ids: string[];
  uuid: UUID;
  session_id: string;
};

SDKHookStartedMessage

Emitted when a hook begins executing.

type SDKHookStartedMessage = {
  type: "system";
  subtype: "hook_started";
  hook_id: string;
  hook_name: string;
  hook_event: string;
  uuid: UUID;
  session_id: string;
};

SDKHookProgressMessage

Emitted while a hook is running, with stdout/stderr output.

type SDKHookProgressMessage = {
  type: "system";
  subtype: "hook_progress";
  hook_id: string;
  hook_name: string;
  hook_event: string;
  stdout: string;
  stderr: string;
  output: string;
  uuid: UUID;
  session_id: string;
};

SDKHookResponseMessage

Emitted when a hook finishes executing.

type SDKHookResponseMessage = {
  type: "system";
  subtype: "hook_response";
  hook_id: string;
  hook_name: string;
  hook_event: string;
  output: string;
  stdout: string;
  stderr: string;
  exit_code?: number;
  outcome: "success" | "error" | "cancelled";
  uuid: UUID;
  session_id: string;
};

SDKToolProgressMessage

Emitted periodically while a tool is executing to indicate progress.

type SDKToolProgressMessage = {
  type: "tool_progress";
  tool_use_id: string;
  tool_name: string;
  parent_tool_use_id: string | null;
  elapsed_time_seconds: number;
  task_id?: string;
  uuid: UUID;
  session_id: string;
};

SDKAuthStatusMessage

Emitted during authentication flows.

type SDKAuthStatusMessage = {
  type: "auth_status";
  isAuthenticating: boolean;
  output: string[];
  error?: string;
  uuid: UUID;
  session_id: string;
};

SDKTaskStartedMessage

Emitted when a background task begins. The task_type field is "local_bash" for background Bash commands and Monitor watches, "local_agent" for subagents, or "remote_agent".

type SDKTaskStartedMessage = {
  type: "system";
  subtype: "task_started";
  task_id: string;
  tool_use_id?: string;
  description: string;
  task_type?: string;
  uuid: UUID;
  session_id: string;
};

SDKTaskProgressMessage

Emitted periodically while a subagent or background task is running. The summary field is populated only when agentProgressSummaries is enabled.

type SDKTaskProgressMessage = {
  type: "system";
  subtype: "task_progress";
  task_id: string;
  tool_use_id?: string;
  description: string;
  subagent_type?: string;
  usage: {
    total_tokens: number;
    tool_uses: number;
    duration_ms: number;
  };
  last_tool_name?: string;
  summary?: string;
  uuid: UUID;
  session_id: string;
};

SDKTaskUpdatedMessage

Emitted when a background task's state changes, such as when it transitions from running to completed. Merge patch into your local task map keyed by task_id. The end_time field is a Unix epoch timestamp in milliseconds, comparable with Date.now().

type SDKTaskUpdatedMessage = {
  type: "system";
  subtype: "task_updated";
  task_id: string;
  patch: {
    status?: "pending" | "running" | "completed" | "failed" | "killed";
    description?: string;
    end_time?: number;
    total_paused_ms?: number;
    error?: string;
    is_backgrounded?: boolean;
  };
  uuid: UUID;
  session_id: string;
};

SDKFilesPersistedEvent

Emitted when file checkpoints are persisted to disk.

type SDKFilesPersistedEvent = {
  type: "system";
  subtype: "files_persisted";
  files: { filename: string; file_id: string }[];
  failed: { filename: string; error: string }[];
  processed_at: string;
  uuid: UUID;
  session_id: string;
};

SDKRateLimitEvent

Emitted when the session encounters a rate limit.

type SDKRateLimitEvent = {
  type: "rate_limit_event";
  rate_limit_info: {
    status: "allowed" | "allowed_warning" | "rejected";
    resetsAt?: number;
    utilization?: number;
  };
  uuid: UUID;
  session_id: string;
};

SDKLocalCommandOutputMessage

Output from a local slash command (for example, /voice or /usage). Displayed as assistant-style text in the transcript.

type SDKLocalCommandOutputMessage = {
  type: "system";
  subtype: "local_command_output";
  content: string;
  uuid: UUID;
  session_id: string;
};

SDKPromptSuggestionMessage

Emitted after each turn when promptSuggestions is enabled. Contains a predicted next user prompt.

type SDKPromptSuggestionMessage = {
  type: "prompt_suggestion";
  suggestion: string;
  uuid: UUID;
  session_id: string;
};

AbortError

Custom error class for abort operations.

class AbortError extends Error {}

Sandbox Configuration

SandboxSettings

Configuration for sandbox behavior. Use this to enable command sandboxing and configure network restrictions programmatically.

type SandboxSettings = {
  enabled?: boolean;
  autoAllowBashIfSandboxed?: boolean;
  excludedCommands?: string[];
  allowUnsandboxedCommands?: boolean;
  network?: SandboxNetworkConfig;
  filesystem?: SandboxFilesystemConfig;
  ignoreViolations?: Record<string, string[]>;
  enableWeakerNestedSandbox?: boolean;
  ripgrep?: { command: string; args?: string[] };
};

Example usage

import { query } from "@anthropic-ai/claude-agent-sdk";

for await (const message of query({
  prompt: "Build and test my project",
  options: {
    sandbox: {
      enabled: true,
      autoAllowBashIfSandboxed: true,
      network: {
        allowLocalBinding: true
      }
    }
  }
})) {
  if ("result" in message) console.log(message.result);
}

SandboxNetworkConfig

Network-specific configuration for sandbox mode.

type SandboxNetworkConfig = {
  allowedDomains?: string[];
  deniedDomains?: string[];
  allowManagedDomainsOnly?: boolean;
  allowLocalBinding?: boolean;
  allowUnixSockets?: string[];
  allowAllUnixSockets?: boolean;
  httpProxyPort?: number;
  socksProxyPort?: number;
};

SandboxFilesystemConfig

Filesystem-specific configuration for sandbox mode.

type SandboxFilesystemConfig = {
  allowWrite?: string[];
  denyWrite?: string[];
  denyRead?: string[];
};

Permissions Fallback for Unsandboxed Commands

When allowUnsandboxedCommands is enabled, the model can request to run commands outside the sandbox by setting dangerouslyDisableSandbox: true in the tool input. These requests fall back to the existing permissions system, meaning your canUseTool handler is invoked, allowing you to implement custom authorization logic.

import { query } from "@anthropic-ai/claude-agent-sdk";

for await (const message of query({
  prompt: "Deploy my application",
  options: {
    sandbox: {
      enabled: true,
      allowUnsandboxedCommands: true // Model can request unsandboxed execution
    },
    permissionMode: "default",
    canUseTool: async (tool, input) => {
      // Check if the model is requesting to bypass the sandbox
      if (tool === "Bash" && input.dangerouslyDisableSandbox) {
        // The model is requesting to run this command outside the sandbox
        console.log(`Unsandboxed command requested: ${input.command}`);

        if (isCommandAuthorized(input.command)) {
          return { behavior: "allow" as const, updatedInput: input };
        }
        return {
          behavior: "deny" as const,
          message: "Command not authorized for unsandboxed execution"
        };
      }
      return { behavior: "allow" as const, updatedInput: input };
    }
  }
})) {
  if ("result" in message) console.log(message.result);
}

This pattern enables you to:

• Audit model requests: Log when the model requests unsandboxed execution
• Implement allowlists: Only permit specific commands to run unsandboxed
• Add approval workflows: Require explicit authorization for privileged operations

See also

• SDK overview - General SDK concepts
• Python SDK reference - Python SDK documentation
• CLI reference - Command-line interface
• Common workflows - Step-by-step guides