# Tool reference
Directory of Anthropic-provided tools and reference for optional tool definition properties.
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This page is a reference for the tools Anthropic provides and the optional properties you can set on any tool definition. For a conceptual introduction to tool use, see [Tool use with Claude](/docs/en/agents-and-tools/tool-use/overview). For guidance on implementing tool use in your application, see [Define tools](/docs/en/agents-and-tools/tool-use/define-tools).
## Anthropic-provided tools
Anthropic provides two kinds of tools: **server tools** that execute on Anthropic's infrastructure, and **client tools** where Anthropic defines the schema but your application handles execution. Both kinds appear in your request's `tools` array alongside any user-defined tools.
| Tool | `type` | Execution | Status |
| ----------------------------------------------------------------------------- | ---------------------------------------------------------------------- | --------- | ------------------------------------------------------------- |
| [Web search tool](/docs/en/agents-and-tools/tool-use/web-search-tool) | `web_search_20260209`
`web_search_20250305` | Server | GA |
| [Web fetch tool](/docs/en/agents-and-tools/tool-use/web-fetch-tool) | `web_fetch_20260209`
`web_fetch_20250910` | Server | GA |
| [Code execution tool](/docs/en/agents-and-tools/tool-use/code-execution-tool) | `code_execution_20260120`
`code_execution_20250825` | Server | GA |
| [Advisor tool](/docs/en/agents-and-tools/tool-use/advisor-tool) | `advisor_20260301` | Server | Beta: `advisor-tool-2026-03-01` |
| [Tool search tool](/docs/en/agents-and-tools/tool-use/tool-search-tool) | `tool_search_tool_regex_20251119`
`tool_search_tool_bm25_20251119` | Server | GA |
| [MCP connector](/docs/en/agents-and-tools/mcp-connector) | `mcp_toolset` | Server | Beta: `mcp-client-2025-11-20` |
| [Memory tool](/docs/en/agents-and-tools/tool-use/memory-tool) | `memory_20250818` | Client | GA |
| [Bash tool](/docs/en/agents-and-tools/tool-use/bash-tool) | `bash_20250124` | Client | GA |
| [Text editor tool](/docs/en/agents-and-tools/tool-use/text-editor-tool) | `text_editor_20250728`
`text_editor_20250124` | Client | GA |
| [Computer use tool](/docs/en/agents-and-tools/tool-use/computer-use-tool) | `computer_20251124`
`computer_20250124` | Client | Beta: `computer-use-2025-11-24`
`computer-use-2025-01-24` |
For model compatibility, see each tool's page. Supported models vary by tool and by tool version.
The tool search `type` values also accept undated aliases:
`tool_search_tool_regex` and `tool_search_tool_bm25`. These resolve to the
latest dated version.
### Tool versioning
Most Anthropic-provided tools carry a `_YYYYMMDD` suffix in the `type` string. A new version is released when the tool's behavior, schema, or model support changes. Older versions remain available so that existing integrations continue to work.
When a tool has multiple active versions, the relationship between them varies:
- **Capability-keyed:** `web_search_20260209` and `web_fetch_20260209` add dynamic content filtering over their predecessors. `code_execution_20260120` adds [programmatic tool calling](/docs/en/agents-and-tools/tool-use/programmatic-tool-calling) from within the sandbox. In each case, both the new and old versions are current; which one you use depends on whether you need the new capability.
- **Model-keyed:** `text_editor_20250728` is for Claude 4 models and `text_editor_20250124` is for earlier models. The version you use depends on the model you target.
- **Variant, not version:** `tool_search_tool_regex_20251119` and `tool_search_tool_bm25_20251119` are two search algorithms released together. Neither supersedes the other.
- **Legacy:** `code_execution_20250522` supports only Python. `code_execution_20250825` adds Bash and file operations.
The `mcp_toolset` type is not date-versioned; versioning is carried in the `anthropic-beta` header instead.
## Tool definition properties
Every tool in the `tools` array, including user-defined tools, accepts optional properties that control how the tool is loaded, who can call it, and how its inputs are validated. These properties compose: you can set `defer_loading` and `cache_control` and `strict` on the same tool.
| Property | Purpose | Available on | Detailed guide |
| ----------------------- | --------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
| `cache_control` | Set a prompt-cache breakpoint at this tool definition | All tools | [Prompt caching](/docs/en/build-with-claude/prompt-caching) |
| `strict` | Guarantee schema validation on tool names and inputs | All tools except `mcp_toolset` | [Strict tool use](/docs/en/agents-and-tools/tool-use/strict-tool-use) |
| `defer_loading` | Exclude the tool from the initial system prompt; load it on demand when tool search returns a `tool_reference` for it | All tools (for `mcp_toolset`, see [tool configuration](/docs/en/agents-and-tools/mcp-connector#mcp-toolset-configuration)) | [Tool search tool](/docs/en/agents-and-tools/tool-use/tool-search-tool) |
| `allowed_callers` | Restrict which callers can call the tool | All tools except `mcp_toolset` | [Programmatic tool calling](/docs/en/agents-and-tools/tool-use/programmatic-tool-calling#the-allowed-callers-field) |
| `input_examples` | Provide example input objects to help Claude understand how to call the tool | User-defined and Anthropic-schema client tools. Not available on server tools. | [Define tools](/docs/en/agents-and-tools/tool-use/define-tools#providing-tool-use-examples) |
| `eager_input_streaming` | Enable fine-grained input streaming (`true`) or keep standard buffered streaming (`false`) for this tool | User-defined tools only | [Fine-grained tool streaming](/docs/en/agents-and-tools/tool-use/fine-grained-tool-streaming) |
### `allowed_callers` values
`allowed_callers` is an array that accepts any combination of:
| Value | Meaning |
| --------------------------- | ----------------------------------------------------------------------------------------------------------------- |
| `"direct"` | The model can call this tool directly in a `tool_use` block. This is the default if `allowed_callers` is omitted. |
| `"code_execution_20260120"` | Code running inside a `code_execution_20260120` sandbox can call this tool. |
Omitting `"direct"` from the array (for example, `"allowed_callers": ["code_execution_20260120"]`) means the tool is callable only from within code execution. The response's `tool_use` block includes a `caller` field that identifies which caller called the tool. See [Programmatic tool calling](/docs/en/agents-and-tools/tool-use/programmatic-tool-calling#the-allowed-callers-field) for the full treatment, including the `caller` response shape and error behavior.
### `defer_loading` and prompt caching
Tools with `defer_loading: true` are stripped from the rendered tools section before the cache key is computed. They don't appear in the system-prompt prefix at all. When tool search discovers a deferred tool and returns a `tool_reference` for it, the tool's full definition is expanded inline at that point in the conversation body, not in the prefix.
This means `defer_loading: true` preserves your prompt cache. You can add deferred tools to a request without invalidating an existing cache entry, and the cache remains valid across the turn where the tool is discovered and the turn where it's called.
For how to combine `defer_loading` with `cache_control` breakpoints, see the [Tool search tool prompt caching guidance](/docs/en/agents-and-tools/tool-use/tool-search-tool#prompt-caching).