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HomeDocsClaude Developer Platform 21 Oct 2026
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tool-use-with-prompt-caching changedagents-and-tools/tool-use/tool-use-with-prompt-caching

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4343For `mcp_toolset`, the `cache_control` breakpoint lands on the last tool in the set. You don't control tool order within an MCP toolset, so place the breakpoint on the `mcp_toolset` entry itself and the API applies it to the final expanded tool.
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45The [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) and [browser use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) toolset entries follow the same rule: place `cache_control` on the toolset entry itself, and the breakpoint lands after the toolset's definition. It isn't accepted inside a member's `configs` entry, because the toolset's members load as one definition. Within a [batch action](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#batch-actions), a `cache_control` marker on any of the turn's member `tool_use` or `tool_result` blocks is accepted and takes effect at the end of that batch, so several markers in one batch act as a single breakpoint. Each marker still counts toward the request's limit of [four breakpoints](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#when-to-use-multiple-breakpoints), so use one per turn.
45The [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) and [browser use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) toolset entries follow the same rule: place `cache_control` on the toolset entry itself, and the breakpoint lands after the toolset's definition. It isn't accepted inside a member's `configs` entry, because the toolset's members load as one definition. Within a [batch action](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#batch-actions), a `cache_control` marker on any of the turn's member `tool_use` or `tool_result` blocks is accepted and takes effect at the end of that batch, so several markers in one batch act as a single breakpoint. Each marker still counts toward the request's limit of [four breakpoints](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#when-to-use-multiple-breakpoints), so use one for each turn.
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4747## defer\_loading and cache preservation
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7575When your request has prompt caching enabled and Claude uses a [server tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/server-tools) such as web search, web fetch, or code execution, the API automatically places a cache breakpoint on the server tool result before running the next iteration of the agentic loop. This lets later iterations within the same request read the growing prefix from cache instead of reprocessing it.
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77This automatic breakpoint always uses the default 5-minute TTL, independent of any TTL you set on your own `cache_control` markers. In the response `usage`, these writes appear under `cache_creation.ephemeral_5m_input_tokens`, so you may see 5-minute cache writes even when every `cache_control` you set uses a 1-hour TTL.
77This automatic breakpoint always uses the default 5-minute TTL, independent of any TTL you set on your own `cache_control` markers. In the response `usage`, these writes appear under `cache_creation.ephemeral_5m_input_tokens`, so you might see 5-minute cache writes even when every `cache_control` you set uses a 1-hour TTL.
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7979This behavior only applies when your request already has at least one `cache_control` marker. Requests without prompt caching do not receive the automatic breakpoint.
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