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Python: fix(mcp): do not duplicate structuredContent when content present #8274

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Merged
Eduard van Valkenburg (eavanvalkenburg) merged 4 commits into from
Sep 15, 2026
Merged

Python: fix(mcp): do not duplicate structuredContent when content present #8274

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93cb102
fix(mcp): do not duplicate structuredContent when content present
ktz03 Sep 10, 2026
6d58210
test(mcp): align expectations with single content+structured item
ktz03 Sep 11, 2026
dbec565
fix(mcp): add explicit tool_result_content selection policy
ktz03 Sep 14, 2026
c451f7c
fix(mcp): document tool_result_content and tighten test typing
ktz03 Sep 15, 2026
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5 changes: 4 additions & 1 deletion python/packages/core/agent_framework/_mcp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1110,7 +1110,10 @@ def _parse_tool_result_from_mcp(
case _:
result.append(Content.from_text(str(item), **additional_kwargs))

if mcp_type.structuredContent is not None:
# Prefer content blocks for the model-visible result. structuredContent is
# still retained on the Host payload; appending it again here duplicates
# what many servers already serialize into content (#7866).
if mcp_type.structuredContent is not None and not result:
result.append(Content.from_text(json.dumps(mcp_type.structuredContent, default=str), **additional_kwargs))
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if not result:
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8 changes: 2 additions & 6 deletions python/packages/core/tests/core/test_mcp.py
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Expand Up @@ -546,21 +546,17 @@ def test_parse_tool_result_from_mcp_structured_content_only():


def test_parse_tool_result_from_mcp_structured_content_with_text():
"""Test that structuredContent is appended alongside regular content items."""
"""When content is present, do not also dump structuredContent into model text (#7866)."""
mcp_result = types.CallToolResult(
content=[types.TextContent(type="text", text="Summary")],
structuredContent={"data": [1, 2, 3]},
)
result = _HELPER_MCP_TOOL._parse_tool_result_from_mcp(mcp_result)

assert isinstance(result, list)
assert len(result) == 2
assert len(result) == 1
assert result[0].type == "text"
assert result[0].text == "Summary"
assert result[1].type == "text"
assert result[1].text is not None
parsed = json.loads(result[1].text)
assert parsed == {"data": [1, 2, 3]}


async def test_generated_mcp_tool_preserves_complete_host_payload_once() -> None:
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