feat(core): Add support for map parameter type

This PR introduces support for the `map` parameter type in the Python SDKs, aligning it with the recent MCP Toolbox server enhancements ([#928](googleapis/genai-toolbox#928)). This allows tools to define parameters that are key-value pairs, either as a generic map with mixed-type values or as a strictly typed map.

## Changes
* The `ParameterSchema` in `protocol.py` has been updated to include an optional `valueType` field.
* The internal `__get_type` method now correctly resolves the `map` type to the appropriate Python `dict` type hint:
  * `dict[str, Any]` for generic maps (when `valueType` is omitted).
  * `dict[str, <type>]` for typed maps (e.g., `dict[str, str]`, `dict[str, int]`).

## Testing
* Added extensive unit tests to `test_protocol.py` to ensure the `map` type is handled correctly.
* Test coverage includes:
  * Generic (untyped) maps.
  * Typed maps for `string`, `integer`, `float`, and `boolean`.
* Optional maps.
* Error handling for unsupported `valueType`.

> [!NOTE]
> No modifications were required in `toolbox-langchain` or `toolbox-llamaindex`. They inherit this new functionality directly from `toolbox-core`.

Author: anubhav756

packages/toolbox-core/src/toolbox_core/protocol.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 from inspect import Parameter
-from typing import Optional, Type
+from typing import Any, Optional, Type
 
 from pydantic import BaseModel
 
@@ -29,6 +29,7 @@ class ParameterSchema(BaseModel):
     description: str
     authSources: Optional[list[str]] = None
     items: Optional["ParameterSchema"] = None
+    valueType: Optional[str] = None
 
     def __get_type(self) -> Type:
         base_type: Type
@@ -44,6 +45,20 @@ def __get_type(self) -> Type:
             if self.items is None:
                 raise Exception("Unexpected value: type is 'list' but items is None")
             base_type = list[self.items.__get_type()]  # type: ignore
+        elif self.type == "map":
+            if self.valueType:
+                if self.valueType == "string":
+                    base_type = dict[str, str]
+                elif self.valueType == "integer":
+                    base_type = dict[str, int]
+                elif self.valueType == "float":
+                    base_type = dict[str, float]
+                elif self.valueType == "boolean":
+                    base_type = dict[str, bool]
+                else:
+                    raise ValueError(f"Unsupported map value type: {self.valueType}")
+            else:
+                base_type = dict[str, Any]
         else:
             raise ValueError(f"Unsupported schema type: {self.type}")
 

packages/toolbox-core/tests/test_protocol.py

@@ -14,7 +14,7 @@
 
 
 from inspect import Parameter
-from typing import Optional
+from typing import Any, Optional
 
 import pytest
 
@@ -170,3 +170,101 @@ def test_parameter_schema_array_optional():
     assert param.annotation == expected_type
     assert param.kind == Parameter.POSITIONAL_OR_KEYWORD
     assert param.default is None
+
+def test_parameter_schema_map_generic():
+    """Tests ParameterSchema with a generic 'map' type."""
+    schema = ParameterSchema(name="metadata", type="map", description="Some metadata")
+    expected_type = dict[str, Any]
+    assert schema._ParameterSchema__get_type() == expected_type
+
+    param = schema.to_param()
+    assert isinstance(param, Parameter)
+    assert param.name == "metadata"
+    assert param.annotation == expected_type
+    assert param.kind == Parameter.POSITIONAL_OR_KEYWORD
+
+
+def test_parameter_schema_map_typed_string():
+    """Tests ParameterSchema with a typed 'map' type (string values)."""
+    schema = ParameterSchema(
+        name="headers",
+        type="map",
+        description="HTTP headers",
+        valueType="string",
+    )
+    expected_type = dict[str, str]
+    assert schema._ParameterSchema__get_type() == expected_type
+
+    param = schema.to_param()
+    assert param.annotation == expected_type
+
+
+def test_parameter_schema_map_typed_integer():
+    """Tests ParameterSchema with a typed 'map' type (integer values)."""
+    schema = ParameterSchema(
+        name="user_scores",
+        type="map",
+        description="User scores",
+        valueType="integer",
+    )
+    expected_type = dict[str, int]
+    assert schema._ParameterSchema__get_type() == expected_type
+    param = schema.to_param()
+    assert param.annotation == expected_type
+
+
+def test_parameter_schema_map_typed_float():
+    """Tests ParameterSchema with a typed 'map' type (float values)."""
+    schema = ParameterSchema(
+        name="item_prices",
+        type="map",
+        description="Item prices",
+        valueType="float",
+    )
+    expected_type = dict[str, float]
+    assert schema._ParameterSchema__get_type() == expected_type
+    param = schema.to_param()
+    assert param.annotation == expected_type
+
+
+def test_parameter_schema_map_typed_boolean():
+    """Tests ParameterSchema with a typed 'map' type (boolean values)."""
+    schema = ParameterSchema(
+        name="feature_flags",
+        type="map",
+        description="Feature flags",
+        valueType="boolean",
+    )
+    expected_type = dict[str, bool]
+    assert schema._ParameterSchema__get_type() == expected_type
+    param = schema.to_param()
+    assert param.annotation == expected_type
+
+
+def test_parameter_schema_map_optional():
+    """Tests an optional ParameterSchema with a 'map' type."""
+    schema = ParameterSchema(
+        name="optional_metadata",
+        type="map",
+        description="Optional metadata",
+        required=False,
+    )
+    expected_type = Optional[dict[str, Any]]
+    assert schema._ParameterSchema__get_type() == expected_type
+    param = schema.to_param()
+    assert param.annotation == expected_type
+    assert param.default is None
+
+
+def test_parameter_schema_map_unsupported_value_type_error():
+    """Tests that an unsupported map valueType raises ValueError."""
+    unsupported_type = "custom_object"
+    schema = ParameterSchema(
+        name="custom_data",
+        type="map",
+        description="Custom data map",
+        valueType=unsupported_type,
+    )
+    expected_error_msg = f"Unsupported map value type: {unsupported_type}"
+    with pytest.raises(ValueError, match=expected_error_msg):
+        schema._ParameterSchema__get_type()