Python: fix(python): add __str__ to ChatMessage to prevent repr in display output#2565
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…tput When a ChatMessage contains only tool calls (no TextContent), code like `str(message)` would return Python's default repr: "<agent_framework._types.ChatMessage object at 0x...>" This bug manifests in MagenticAgentExecutor._invoke_agent() at line 1730 where `text = last.text or str(last)` uses str(last) as fallback when .text is empty (which happens for tool-call-only messages). Changes: - Add __str__ method to ChatMessage that returns text content or formatted tool call summary, never repr - Add __repr__ method to ChatMessage for better debugging - Add comprehensive tests for both methods The buggy line 1730 now works correctly without modification because str(ChatMessage) returns meaningful content. Fixes microsoft#2562
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Summary
When a
ChatMessagecontains only tool calls (no text),str(message)returns Python's default repr (<agent_framework._types.ChatMessage object at 0x...>) instead of meaningful content.This PR adds
__str__and__repr__methods toChatMessage:__str__returns text content when present, or a formatted summary of tool calls__repr__returns debug-friendly output with role, text preview, and content countThe Bug
In
MagenticAgentExecutor._invoke_agent()line 1730:When the message has only
FunctionCallContent(noTextContent),.textreturns empty string, triggering thestr(last)fallback—which produced the repr garbage.The Fix
By adding
__str__toChatMessage, the existing code works correctly without modification. This also future-proofs any other code that callsstr()on aChatMessage.Test Plan
Fixes #2562