Symptom
In a Temporal agent, an MCP tool that raises ModelRetry, such as a fetch that hits a 404, fails the activity, and Temporal retries it endlessly instead of handing control back to the agent.
Evidence what you'll see
- Reproduced by adding the mcp-server-fetch toolset to the Temporal example
- The activity keeps retrying
- Reported on version 1.8.0
Cause
The Temporal MCP activity let ModelRetry escape as an activity failure; only function toolsets passed it back to the agent as a result.
Fix steps
0 of 1 done
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Verify the fix worked
- Ask the Temporal agent to fetch a page that returns 404 and confirm the model gets a retry prompt and the workflow moves on.
Sources and credit
Summarized in our own words from these public reports. Credit goes to their authors.
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