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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

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Claude Code v2.1.187

MCP tool idle timeout detection

What

MCP tools that stop sending progress or responses are now detected and aborted after a configurable timeout. A new env var controls the timeout duration.

Usage
# Set timeout in milliseconds (default is built-in; 0 disables timeout)
export CLAUDE_CODE_MCP_TOOL_IDLE_TIMEOUT=120000   # 2 minutes
export CLAUDE_CODE_MCP_TOOL_IDLE_TIMEOUT=0        # disable
Details
  • When an MCP tool produces no output for the configured duration, Claude aborts the call and reports the timeout
  • Error message includes the tool name and duration: "MCP server X tool Y sent no response or progress for Ns; aborting"
  • A new McpResponseSchemaError is thrown and surfaced when an MCP server returns a result that fails schema validation, with a description of what was wrong
Evidence

New timeout guard (search for "CLAUDE_CODE_MCP_TOOL_IDLE_TIMEOUT" or "MCP tool idle timeout")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.187 →