[Bug] Invalid parameter: messages with role 'tool' must be a response to a preceding message with 'tool_calls'.

[Kinbaum]

When using an agent network (routing agent hands off to a specialized weather agent), the first weather request works correctly, but subsequent requests that call the tool fail with the following error:

Invalid parameter: messages with role 'tool' must be a response to a preceding message with 'tool_calls'

Reproduction steps:

1. Setup - Create an agent network with:
   • A routing agent that receives user prompts and forwards to a specialized agent.
   • A weather agent that calls an external tool (the weather tool) and returns a response.

2. Interaction
   • Ask the routing agent for weather in location A (e.g., "Is it snowing in Dallas TX?").
   • Routing agent forwards to the weather agent.
   • Weather agent calls the tool and returns a message with role "tool" (this succeeds).
   • Ask the routing agent for weather in a different location B (e.g., "How about Tampa FL?")
   • Routing agent forwards to the weather agent again and the weather agent attempts to call the same tool.

Note

Sometimes this succeeds and you'll need to ask it a few more times. See the recording.
Model is azure/gpt-5 and azure/gpt-5-mini

Sequence.01.mp4

[Kinbaum]

After a bit of testing, I patched v1.0.8 with PR #104 and that seems to have resolved my issue described.
@pontusab Can we please get eyes on that PR and a merge?

[Alain00]

I think this might be also related to #120