fix: avoid UserWarning in _build_response_log when response has funct…

[AdeevMardia2008]

Fix: _build_response_log() triggers genai SDK UserWarning on every tool call

Closes #4685

What's the problem?

Every time an ADK agent invokes a tool, the debug logger calls _build_response_log(response), which includes resp.text in its f-string:

return f"""
LLM Response:
...
Text:
{resp.text}   # ← triggers UserWarning
...
"""

The GenerateContentResponse.text property in the google-genai SDK raises a UserWarning whenever the response contains non-text parts — which is exactly the case when the model responds with a function_call. This means every single tool invocation floods the log with warnings like:

UserWarning: Warning: there are non-text parts in the response: ['function_call'],returning concatenated text result from text parts, check `response.parts` directly to inspect non-text parts
  warnings.warn(

Since _build_response_log is only called inside if logger.isEnabledFor(logging.DEBUG), this hits any developer who enables debug logging — which is common when debugging agents.

Root cause

GenerateContentResponse.text is a convenience property that warns when mixed content is present. Accessing it in a log formatter silently poisons the log output whenever agents use tools.

Fix

Replace resp.text with a manual join of only the text parts from resp.candidates, bypassing the warning entirely:

# Before
return f"""
...
Text:
{resp.text}
...
"""

# After — safe extraction with no warning
text_parts = []
if resp.candidates:
    for candidate in resp.candidates:
        if candidate.content and candidate.content.parts:
            text_parts.extend(
                p.text for p in candidate.content.parts if p.text is not None
            )
text = ''.join(text_parts)

return f"""
...
Text:
{text}
...
"""

This produces identical output when only text parts are present, and correctly shows an empty string (rather than a warning) when the response is a function call — which is the right behavior for a debug log.

Files changed

• src/google/adk/models/google_llm.py — 10-line change inside _build_response_log(), no other logic touched

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[adk-bot]

Thank you @AdeevMardia2008 for your contribution! 🎉

Your changes have been successfully imported and merged via Copybara in commit f022307.

Closing this PR as the changes are now in the main branch.