What
Claude Code can offer its own tools to another program over MCP (a protocol for connecting tools). When such a call comes from another host:
- A call that was already started is not run again. It returns "was not run again: this very call was already started here once".
- A permission request that matches one still waiting for an answer is joined to it rather than asked a second time.
- A permission request that was declined is now acknowledged and answered with a result, instead of falling through to the general case. The path for a request that was not honoured now also reports which part was affected.
Why
A host that retries a call no longer causes the tool to run twice or a second permission prompt to appear, and a declined permission is reported back to the host.