From 3256a679da3e0fb6f18b26057e87f5284680cb58 Mon Sep 17 00:00:00 2001 From: Brian Fox <878612+onematchfox@users.noreply.github.com> Date: Wed, 25 Feb 2026 10:10:09 -0800 Subject: [PATCH] fix(tools): Handle JSON Schema boolean schemas in Gemini schema conversion Merge https://github.com/google/adk-python/pull/4531 **Problem:** JSON Schema allows `true` and `false` as valid boolean schemas, where `true` accepts any value and `false` rejects all values. Some MCP servers use this pattern for unconstrained fields. E.g. [mcp-grafana](https://github.com/grafana/mcp-grafana) - see [grafana-mcp-list-tools.json](https://github.com/user-attachments/files/25392430/grafana-mcp-list-tools.json) which was obtained from `tools/list` The schema sanitizer previously passed booleans through unchanged, causing a Pydantic ValidationError when `_ExtendedJSONSchema` tried to validate them as schema objects. ``` 1 validation error for _ExtendedJSONSchema properties.data.items.properties.model Input should be a valid dictionary or object to extract fields from [type=model_attributes_type, input_value=True, input_type=bool] For further information visit https://errors.pydantic.dev/2.12/v/model_attributes_type Traceback (most recent call last): ... File "/.foo/.venv/lib/python3.13/site-packages/google/adk/runners.py", line 561, in run_async async for event in agen: yield event File "/.foo/.venv/lib/python3.13/site-packages/google/adk/runners.py", line 549, in _run_with_trace async for event in agen: yield event File "/.foo/.venv/lib/python3.13/site-packages/google/adk/runners.py", line 778, in _exec_with_plugin async for event in agen: ...<64 lines>... yield event File "/.foo/.venv/lib/python3.13/site-packages/google/adk/runners.py", line 538, in execute async for event in agen: yield event File "/.foo/.venv/lib/python3.13/site-packages/google/adk/agents/base_agent.py", line 294, in run_async async for event in agen: yield event File "/.foo/.venv/lib/python3.13/site-packages/google/adk/agents/llm_agent.py", line 468, in _run_async_impl async for event in agen: ...<5 lines>... should_pause = True File "/.foo/.venv/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 427, in run_async async for event in agen: last_event = event yield event File "/.foo/.venv/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 446, in _run_one_step_async async for event in agen: yield event File "/.foo/.venv/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 578, in _preprocess_async await tool.process_llm_request( tool_context=tool_context, llm_request=llm_request ) File "/.foo/.venv/lib/python3.13/site-packages/google/adk/tools/base_tool.py", line 129, in process_llm_request llm_request.append_tools([self]) ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^ File "/.foo/.venv/lib/python3.13/site-packages/google/adk/models/llm_request.py", line 255, in append_tools declaration = tool._get_declaration() File "/.foo/.venv/lib/python3.13/site-packages/google/adk/tools/mcp_tool/mcp_tool.py", line 200, in _get_declaration parameters = _to_gemini_schema(input_schema) File "/.foo/.venv/lib/python3.13/site-packages/google/adk/tools/_gemini_schema_util.py", line 218, in _to_gemini_schema json_schema=_ExtendedJSONSchema.model_validate(sanitized_schema), ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^ File "/.foo/.venv/lib/python3.13/site-packages/pydantic/main.py", line 716, in model_validate return cls.__pydantic_validator__.validate_python( ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^ obj, ^^^^ ...<5 lines>... by_name=by_name, ^^^^^^^^^^^^^^^^ ) ^ pydantic_core._pydantic_core.ValidationError: 1 validation error for _ExtendedJSONSchema properties.data.items.properties.model Input should be a valid dictionary or object to extract fields from [type=model_attributes_type, input_value=True, input_type=bool] For further information visit https://errors.pydantic.dev/2.12/v/model_attributes_type ``` **Solution:** Convert boolean schemas to `{"type": "object"}` as the closest approximation available in Gemini's schema model. Co-authored-by: Xuan Yang COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/4531 from onematchfox:fix-gemini-schema-bool 383ac0c0c3ab78d77be4503f5d6b9ad26c41b0db PiperOrigin-RevId: 875219362 --- src/google/adk/tools/_gemini_schema_util.py | 7 ++ .../tools/test_gemini_schema_util.py | 82 +++++++++++++++++++ 2 files changed, 89 insertions(+) diff --git a/src/google/adk/tools/_gemini_schema_util.py b/src/google/adk/tools/_gemini_schema_util.py index 6a05f6c6..595b41a0 100644 --- a/src/google/adk/tools/_gemini_schema_util.py +++ b/src/google/adk/tools/_gemini_schema_util.py @@ -152,6 +152,13 @@ def _sanitize_schema_formats_for_gemini( ) for item in schema ] + # JSON Schema allows boolean schemas: `true` (accept any value) and `false` + # (reject all values). Gemini has no equivalent for either. `true` is + # approximated as an unconstrained object schema; `false` has no meaningful + # Gemini representation and is also mapped to an object schema as a safe + # fallback so that schema conversion does not crash. + if isinstance(schema, bool): + return {"type": "object"} if not isinstance(schema, dict): return schema diff --git a/tests/unittests/tools/test_gemini_schema_util.py b/tests/unittests/tools/test_gemini_schema_util.py index d8445ab8..b7091903 100644 --- a/tests/unittests/tools/test_gemini_schema_util.py +++ b/tests/unittests/tools/test_gemini_schema_util.py @@ -648,6 +648,88 @@ class TestToGeminiSchema: assert gemini_schema.type == Type.OBJECT assert gemini_schema.properties is None + def test_to_gemini_schema_boolean_true_property(self): + """Tests that a JSON Schema boolean `true` property is handled. + + JSON Schema allows `true` as a schema meaning "accept any value". + Some MCP servers use this pattern for fields whose content is not + further constrained. + """ + openapi_schema = { + "type": "object", + "properties": { + "items": { + "type": "array", + "items": { + "type": "object", + "properties": { + "refId": {"type": "string"}, + "model": True, # JSON Schema boolean schema + }, + }, + } + }, + } + gemini_schema = _to_gemini_schema(openapi_schema) + assert isinstance(gemini_schema, Schema) + items_schema = gemini_schema.properties["items"] + assert items_schema.type == Type.ARRAY + # `model: true` should be converted to an object schema + model_schema = items_schema.items.properties["model"] + assert model_schema.type == Type.OBJECT + + def test_to_gemini_schema_boolean_false_property(self): + """Tests that a JSON Schema boolean `false` property does not raise. + + `false` means "no value is valid" in JSON Schema, which has no Gemini + equivalent. Conversion falls back to an object schema to avoid crashing; + the result is semantically imprecise but safe. + """ + openapi_schema = { + "type": "object", + "properties": { + "anything": False, # JSON Schema boolean schema (reject all) + }, + } + # Should not raise even though `false` has no Gemini equivalent. + gemini_schema = _to_gemini_schema(openapi_schema) + assert isinstance(gemini_schema, Schema) + assert gemini_schema.properties["anything"] is not None + + def test_to_gemini_schema_boolean_true_in_array_items_properties(self): + """Regression test: boolean `true` schema inside array item properties. + + Some MCP servers use `"field": true` in an array item's properties to + indicate an unconstrained field, which is valid JSON Schema. + """ + openapi_schema = { + "type": "object", + "properties": { + "title": {"type": "string"}, + "data": { + "type": "array", + "items": { + "type": "object", + "properties": { + "datasourceUid": {"type": "string"}, + "model": True, + "queryType": {"type": "string"}, + "refId": {"type": "string"}, + }, + }, + }, + }, + "required": ["title", "data"], + } + # Should not raise a ValidationError + gemini_schema = _to_gemini_schema(openapi_schema) + assert isinstance(gemini_schema, Schema) + assert gemini_schema.type == Type.OBJECT + data_schema = gemini_schema.properties["data"] + assert data_schema.type == Type.ARRAY + model_schema = data_schema.items.properties["model"] + assert model_schema.type == Type.OBJECT + class TestToSnakeCase: