fix(kimi,mcp): Moonshot schema sanitizer + MCP schema robustness (#14805)

Fixes a broader class of 'tools.function.parameters is not a valid
moonshot flavored json schema' errors on Nous / OpenRouter aggregators
routing to moonshotai/kimi-k2.6 with MCP tools loaded.

## Moonshot sanitizer (agent/moonshot_schema.py, new)

Model-name-routed (not base-URL-routed) so Nous / OpenRouter users are
covered alongside api.moonshot.ai.  Applied in
ChatCompletionsTransport.build_kwargs when is_moonshot_model(model).

Two repairs:
1. Fill missing 'type' on every property / items / anyOf-child schema
   node (structural walk — only schema-position dicts are touched, not
   container maps like properties/$defs).
2. Strip 'type' at anyOf parents; Moonshot rejects it.

## MCP normalizer hardened (tools/mcp_tool.py)

Draft-07 $ref rewrite from PR #14802 now also does:
- coerce missing / null 'type' on object-shaped nodes (salvages #4897)
- prune 'required' arrays to names that exist in 'properties'
  (salvages #4651; Gemini 400s on dangling required)
- apply recursively, not just top-level

These repairs are provider-agnostic so the same MCP schema is valid on
OpenAI, Anthropic, Gemini, and Moonshot in one pass.

## Crash fix: safe getattr for Tool.inputSchema

_convert_mcp_schema now uses getattr(t, 'inputSchema', None) so MCP
servers whose Tool objects omit the attribute entirely no longer abort
registration (salvages #3882).

## Validation

- tests/agent/test_moonshot_schema.py: 27 new tests (model detection,
  missing-type fill, anyOf-parent strip, non-mutation, real-world MCP
  shape)
- tests/tools/test_mcp_tool.py: 7 new tests (missing / null type,
  required pruning, nested repair, safe getattr)
- tests/agent/transports/test_chat_completions.py: 2 new integration
  tests (Moonshot route sanitizes, non-Moonshot route doesn't)
- Targeted suite: 49 passed
- E2E via execute_code with a realistic MCP tool carrying all three
  Moonshot rejection modes + dangling required + draft-07 refs:
  sanitizer produces a schema valid on Moonshot and Gemini

agent/moonshot_schema.py

@@ -0,0 +1,190 @@
+"""Helpers for translating OpenAI-style tool schemas to Moonshot's schema subset.
+
+Moonshot (Kimi) accepts a stricter subset of JSON Schema than standard OpenAI
+tool calling.  Requests that violate it fail with HTTP 400:
+
+    tools.function.parameters is not a valid moonshot flavored json schema,
+    details: <...>
+
+Known rejection modes documented at
+https://forum.moonshot.ai/t/tool-calling-specification-violation-on-moonshot-api/102
+and MoonshotAI/kimi-cli#1595:
+
+1. Every property schema must carry a ``type``.  Standard JSON Schema allows
+   type to be omitted (the value is then unconstrained); Moonshot refuses.
+2. When ``anyOf`` is used, ``type`` must be on the ``anyOf`` children, not
+   the parent.  Presence of both causes "type should be defined in anyOf
+   items instead of the parent schema".
+
+The ``#/definitions/...`` → ``#/$defs/...`` rewrite for draft-07 refs is
+handled separately in ``tools/mcp_tool._normalize_mcp_input_schema`` so it
+applies at MCP registration time for all providers.
+"""
+
+from __future__ import annotations
+
+import copy
+from typing import Any, Dict, List
+
+# Keys whose values are maps of name → schema (not schemas themselves).
+# When we recurse, we walk the values of these maps as schemas, but we do
+# NOT apply the missing-type repair to the map itself.
+_SCHEMA_MAP_KEYS = frozenset({"properties", "patternProperties", "$defs", "definitions"})
+
+# Keys whose values are lists of schemas.
+_SCHEMA_LIST_KEYS = frozenset({"anyOf", "oneOf", "allOf", "prefixItems"})
+
+# Keys whose values are a single nested schema.
+_SCHEMA_NODE_KEYS = frozenset({"items", "contains", "not", "additionalProperties", "propertyNames"})
+
+
+def _repair_schema(node: Any, is_schema: bool = True) -> Any:
+    """Recursively apply Moonshot repairs to a schema node.
+
+    ``is_schema=True`` means this dict is a JSON Schema node and gets the
+    missing-type + anyOf-parent repairs applied.  ``is_schema=False`` means
+    it's a container map (e.g. the value of ``properties``) and we only
+    recurse into its values.
+    """
+    if isinstance(node, list):
+        # Lists only show up under schema-list keys (anyOf/oneOf/allOf), so
+        # every element is itself a schema.
+        return [_repair_schema(item, is_schema=True) for item in node]
+    if not isinstance(node, dict):
+        return node
+
+    # Walk the dict, deciding per-key whether recursion is into a schema
+    # node, a container map, or a scalar.
+    repaired: Dict[str, Any] = {}
+    for key, value in node.items():
+        if key in _SCHEMA_MAP_KEYS and isinstance(value, dict):
+            # Map of name → schema.  Don't treat the map itself as a schema
+            # (it has no type / properties of its own), but each value is.
+            repaired[key] = {
+                sub_key: _repair_schema(sub_val, is_schema=True)
+                for sub_key, sub_val in value.items()
+            }
+        elif key in _SCHEMA_LIST_KEYS and isinstance(value, list):
+            repaired[key] = [_repair_schema(v, is_schema=True) for v in value]
+        elif key in _SCHEMA_NODE_KEYS:
+            # items / not / additionalProperties: single nested schema.
+            # additionalProperties can also be a bool — leave those alone.
+            if isinstance(value, dict):
+                repaired[key] = _repair_schema(value, is_schema=True)
+            else:
+                repaired[key] = value
+        else:
+            # Scalars (description, title, format, enum values, etc.) pass through.
+            repaired[key] = value
+
+    if not is_schema:
+        return repaired
+
+    # Rule 2: when anyOf is present, type belongs only on the children.
+    if "anyOf" in repaired and isinstance(repaired["anyOf"], list):
+        repaired.pop("type", None)
+        return repaired
+
+    # Rule 1: property schemas without type need one.  $ref nodes are exempt
+    # — their type comes from the referenced definition.
+    if "$ref" in repaired:
+        return repaired
+    return _fill_missing_type(repaired)
+
+
+def _fill_missing_type(node: Dict[str, Any]) -> Dict[str, Any]:
+    """Infer a reasonable ``type`` if this schema node has none."""
+    if "type" in node and node["type"] not in (None, ""):
+        return node
+
+    # Heuristic: presence of ``properties`` → object, ``items`` → array, ``enum``
+    # → type of first enum value, else fall back to ``string`` (safest scalar).
+    if "properties" in node or "required" in node or "additionalProperties" in node:
+        inferred = "object"
+    elif "items" in node or "prefixItems" in node:
+        inferred = "array"
+    elif "enum" in node and isinstance(node["enum"], list) and node["enum"]:
+        sample = node["enum"][0]
+        if isinstance(sample, bool):
+            inferred = "boolean"
+        elif isinstance(sample, int):
+            inferred = "integer"
+        elif isinstance(sample, float):
+            inferred = "number"
+        else:
+            inferred = "string"
+    else:
+        inferred = "string"
+
+    return {**node, "type": inferred}
+
+
+def sanitize_moonshot_tool_parameters(parameters: Any) -> Dict[str, Any]:
+    """Normalize tool parameters to a Moonshot-compatible object schema.
+
+    Returns a deep-copied schema with the two flavored-JSON-Schema repairs
+    applied.  Input is not mutated.
+    """
+    if not isinstance(parameters, dict):
+        return {"type": "object", "properties": {}}
+
+    repaired = _repair_schema(copy.deepcopy(parameters), is_schema=True)
+    if not isinstance(repaired, dict):
+        return {"type": "object", "properties": {}}
+
+    # Top-level must be an object schema
+    if repaired.get("type") != "object":
+        repaired["type"] = "object"
+    if "properties" not in repaired:
+        repaired["properties"] = {}
+
+    return repaired
+
+
+def sanitize_moonshot_tools(tools: List[Dict[str, Any]]) -> List[Dict[str, Any]]:
+    """Apply ``sanitize_moonshot_tool_parameters`` to every tool's parameters."""
+    if not tools:
+        return tools
+
+    sanitized: List[Dict[str, Any]] = []
+    any_change = False
+    for tool in tools:
+        if not isinstance(tool, dict):
+            sanitized.append(tool)
+            continue
+        fn = tool.get("function")
+        if not isinstance(fn, dict):
+            sanitized.append(tool)
+            continue
+        params = fn.get("parameters")
+        repaired = sanitize_moonshot_tool_parameters(params)
+        if repaired is not params:
+            any_change = True
+            new_fn = {**fn, "parameters": repaired}
+            sanitized.append({**tool, "function": new_fn})
+        else:
+            sanitized.append(tool)
+
+    return sanitized if any_change else tools
+
+
+def is_moonshot_model(model: str | None) -> bool:
+    """True for any Kimi / Moonshot model slug, regardless of aggregator prefix.
+
+    Matches bare names (``kimi-k2.6``, ``moonshotai/Kimi-K2.6``) and aggregator-
+    prefixed slugs (``nous/moonshotai/kimi-k2.6``, ``openrouter/moonshotai/...``).
+    Detection by model name covers Nous / OpenRouter / other aggregators that
+    route to Moonshot's inference, where the base URL is the aggregator's, not
+    ``api.moonshot.ai``.
+    """
+    if not model:
+        return False
+    bare = model.strip().lower()
+    # Last path segment (covers aggregator-prefixed slugs)
+    tail = bare.rsplit("/", 1)[-1]
+    if tail.startswith("kimi-") or tail == "kimi":
+        return True
+    # Vendor-prefixed forms commonly used on aggregators
+    if "moonshot" in bare or "/kimi" in bare or bare.startswith("kimi"):
+        return True
+    return False

agent/transports/chat_completions.py

@@ -12,6 +12,7 @@ reasoning configuration, temperature handling, and extra_body assembly.
 import copy
 from typing import Any, Dict, List, Optional
 
+from agent.moonshot_schema import is_moonshot_model, sanitize_moonshot_tools
 from agent.prompt_builder import DEVELOPER_ROLE_MODELS
 from agent.transports.base import ProviderTransport
 from agent.transports.types import NormalizedResponse, ToolCall, Usage
@@ -172,6 +173,11 @@ class ChatCompletionsTransport(ProviderTransport):
 
         # Tools
         if tools:
+            # Moonshot/Kimi uses a stricter flavored JSON Schema.  Rewriting
+            # tool parameters here keeps aggregator routes (Nous, OpenRouter,
+            # etc.) compatible, in addition to direct moonshot.ai endpoints.
+            if is_moonshot_model(model):
+                tools = sanitize_moonshot_tools(tools)
             api_kwargs["tools"] = tools
 
         # max_tokens resolution — priority: ephemeral > user > provider default

tests/agent/test_moonshot_schema.py

@@ -0,0 +1,254 @@
+"""Tests for Moonshot/Kimi flavored-JSON-Schema sanitizer.
+
+Moonshot's tool-parameter validator rejects several shapes that the rest of
+the JSON Schema ecosystem accepts:
+
+1. Properties without ``type`` — Moonshot requires ``type`` on every node.
+2. ``type`` at the parent of ``anyOf`` — Moonshot requires it only inside
+   ``anyOf`` children.
+
+These tests cover the repairs applied by ``agent/moonshot_schema.py``.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from agent.moonshot_schema import (
+    is_moonshot_model,
+    sanitize_moonshot_tool_parameters,
+    sanitize_moonshot_tools,
+)
+
+
+class TestMoonshotModelDetection:
+    """is_moonshot_model() must match across aggregator prefixes."""
+
+    @pytest.mark.parametrize(
+        "model",
+        [
+            "kimi-k2.6",
+            "kimi-k2-thinking",
+            "moonshotai/Kimi-K2.6",
+            "moonshotai/kimi-k2.6",
+            "nous/moonshotai/kimi-k2.6",
+            "openrouter/moonshotai/kimi-k2-thinking",
+            "MOONSHOTAI/KIMI-K2.6",
+        ],
+    )
+    def test_positive_matches(self, model):
+        assert is_moonshot_model(model) is True
+
+    @pytest.mark.parametrize(
+        "model",
+        [
+            "",
+            None,
+            "anthropic/claude-sonnet-4.6",
+            "openai/gpt-5.4",
+            "google/gemini-3-flash-preview",
+            "deepseek-chat",
+        ],
+    )
+    def test_negative_matches(self, model):
+        assert is_moonshot_model(model) is False
+
+
+class TestMissingTypeFilled:
+    """Rule 1: every property must carry a type."""
+
+    def test_property_without_type_gets_string(self):
+        params = {
+            "type": "object",
+            "properties": {"query": {"description": "a bare property"}},
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        assert out["properties"]["query"]["type"] == "string"
+
+    def test_property_with_enum_infers_type_from_first_value(self):
+        params = {
+            "type": "object",
+            "properties": {"flag": {"enum": [True, False]}},
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        assert out["properties"]["flag"]["type"] == "boolean"
+
+    def test_nested_properties_are_repaired(self):
+        params = {
+            "type": "object",
+            "properties": {
+                "filter": {
+                    "type": "object",
+                    "properties": {
+                        "field": {"description": "no type"},
+                    },
+                },
+            },
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        assert out["properties"]["filter"]["properties"]["field"]["type"] == "string"
+
+    def test_array_items_without_type_get_repaired(self):
+        params = {
+            "type": "object",
+            "properties": {
+                "tags": {
+                    "type": "array",
+                    "items": {"description": "tag entry"},
+                },
+            },
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        assert out["properties"]["tags"]["items"]["type"] == "string"
+
+    def test_ref_node_is_not_given_synthetic_type(self):
+        """$ref nodes should NOT get a synthetic type — the referenced
+        definition supplies it, and Moonshot would reject the conflict."""
+        params = {
+            "type": "object",
+            "properties": {"payload": {"$ref": "#/$defs/Payload"}},
+            "$defs": {"Payload": {"type": "object", "properties": {}}},
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        assert "type" not in out["properties"]["payload"]
+        assert out["properties"]["payload"]["$ref"] == "#/$defs/Payload"
+
+
+class TestAnyOfParentType:
+    """Rule 2: type must not appear at the anyOf parent level."""
+
+    def test_parent_type_stripped_when_anyof_present(self):
+        params = {
+            "type": "object",
+            "properties": {
+                "from_format": {
+                    "type": "string",
+                    "anyOf": [
+                        {"type": "string"},
+                        {"type": "null"},
+                    ],
+                },
+            },
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        from_format = out["properties"]["from_format"]
+        assert "type" not in from_format
+        assert "anyOf" in from_format
+
+    def test_anyof_children_missing_type_get_filled(self):
+        params = {
+            "type": "object",
+            "properties": {
+                "value": {
+                    "anyOf": [
+                        {"type": "string"},
+                        {"description": "A typeless option"},
+                    ],
+                },
+            },
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        children = out["properties"]["value"]["anyOf"]
+        assert children[0]["type"] == "string"
+        assert "type" in children[1]
+
+
+class TestTopLevelGuarantees:
+    """The returned top-level schema is always a well-formed object."""
+
+    def test_non_dict_input_returns_empty_object(self):
+        assert sanitize_moonshot_tool_parameters(None) == {"type": "object", "properties": {}}
+        assert sanitize_moonshot_tool_parameters("garbage") == {"type": "object", "properties": {}}
+        assert sanitize_moonshot_tool_parameters([]) == {"type": "object", "properties": {}}
+
+    def test_non_object_top_level_coerced(self):
+        params = {"type": "string"}
+        out = sanitize_moonshot_tool_parameters(params)
+        assert out["type"] == "object"
+        assert "properties" in out
+
+    def test_does_not_mutate_input(self):
+        params = {
+            "type": "object",
+            "properties": {"q": {"description": "no type"}},
+        }
+        snapshot = {
+            "type": params["type"],
+            "properties": {"q": dict(params["properties"]["q"])},
+        }
+        sanitize_moonshot_tool_parameters(params)
+        assert params["type"] == snapshot["type"]
+        assert "type" not in params["properties"]["q"]
+
+
+class TestToolListSanitizer:
+    """sanitize_moonshot_tools() walks an OpenAI-format tool list."""
+
+    def test_applies_per_tool(self):
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "search",
+                    "description": "Search",
+                    "parameters": {
+                        "type": "object",
+                        "properties": {"q": {"description": "query"}},
+                    },
+                },
+            },
+            {
+                "type": "function",
+                "function": {
+                    "name": "noop",
+                    "description": "Does nothing",
+                    "parameters": {"type": "object", "properties": {}},
+                },
+            },
+        ]
+        out = sanitize_moonshot_tools(tools)
+        assert out[0]["function"]["parameters"]["properties"]["q"]["type"] == "string"
+        # Second tool already clean — should be structurally equivalent
+        assert out[1]["function"]["parameters"] == {"type": "object", "properties": {}}
+
+    def test_empty_list_is_passthrough(self):
+        assert sanitize_moonshot_tools([]) == []
+        assert sanitize_moonshot_tools(None) is None
+
+    def test_skips_malformed_entries(self):
+        """Entries without a function dict are passed through untouched."""
+        tools = [{"type": "function"}, {"not": "a tool"}]
+        out = sanitize_moonshot_tools(tools)
+        assert out == tools
+
+
+class TestRealWorldMCPShape:
+    """End-to-end: a realistic MCP-style schema that used to 400 on Moonshot."""
+
+    def test_combined_rewrites(self):
+        # Shape: missing type on a property, anyOf with parent type, array
+        # items without type — all in one tool.
+        params = {
+            "type": "object",
+            "properties": {
+                "query": {"description": "search text"},
+                "filter": {
+                    "type": "string",
+                    "anyOf": [
+                        {"type": "string"},
+                        {"type": "null"},
+                    ],
+                },
+                "tags": {
+                    "type": "array",
+                    "items": {"description": "tag"},
+                },
+            },
+            "required": ["query"],
+        }
+        out = sanitize_moonshot_tool_parameters(params)
+        assert out["properties"]["query"]["type"] == "string"
+        assert "type" not in out["properties"]["filter"]
+        assert out["properties"]["filter"]["anyOf"][0]["type"] == "string"
+        assert out["properties"]["tags"]["items"]["type"] == "string"
+        assert out["required"] == ["query"]

tests/agent/transports/test_chat_completions.py

@@ -238,6 +238,56 @@ class TestChatCompletionsKimi:
         )
         assert kw["extra_body"]["thinking"] == {"type": "disabled"}
 
+    def test_moonshot_tool_schemas_are_sanitized_by_model_name(self, transport):
+        """Aggregator routes (Nous, OpenRouter) hit Moonshot by model name, not base URL."""
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "search",
+                    "description": "Search",
+                    "parameters": {
+                        "type": "object",
+                        "properties": {
+                            "q": {"description": "query"},  # missing type
+                        },
+                    },
+                },
+            },
+        ]
+        kw = transport.build_kwargs(
+            model="moonshotai/kimi-k2.6",
+            messages=[{"role": "user", "content": "Hi"}],
+            tools=tools,
+            max_tokens_param_fn=lambda n: {"max_tokens": n},
+        )
+        assert kw["tools"][0]["function"]["parameters"]["properties"]["q"]["type"] == "string"
+
+    def test_non_moonshot_tools_are_not_mutated(self, transport):
+        """Other models don't go through the Moonshot sanitizer."""
+        original_params = {
+            "type": "object",
+            "properties": {"q": {"description": "query"}},  # missing type
+        }
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "search",
+                    "description": "Search",
+                    "parameters": original_params,
+                },
+            },
+        ]
+        kw = transport.build_kwargs(
+            model="anthropic/claude-sonnet-4.6",
+            messages=[{"role": "user", "content": "Hi"}],
+            tools=tools,
+            max_tokens_param_fn=lambda n: {"max_tokens": n},
+        )
+        # The parameters dict is passed through untouched (no synthetic type)
+        assert "type" not in kw["tools"][0]["function"]["parameters"]["properties"]["q"]
+
 
 class TestChatCompletionsValidate:
 

tests/tools/test_mcp_tool.py

@@ -186,6 +186,111 @@ class TestSchemaConversion:
         assert schema["parameters"]["properties"]["items"]["items"]["$ref"] == "#/$defs/Entry"
         assert schema["parameters"]["$defs"]["Entry"]["properties"]["child"]["$ref"] == "#/$defs/Child"
 
+    def test_missing_type_on_object_is_coerced(self):
+        """Schemas that describe an object but omit ``type`` get type='object'."""
+        from tools.mcp_tool import _normalize_mcp_input_schema
+
+        schema = _normalize_mcp_input_schema({
+            "properties": {"q": {"type": "string"}},
+            "required": ["q"],
+        })
+
+        assert schema["type"] == "object"
+        assert schema["properties"]["q"]["type"] == "string"
+        assert schema["required"] == ["q"]
+
+    def test_null_type_on_object_is_coerced(self):
+        """type: None should be treated like missing type (common MCP server bug)."""
+        from tools.mcp_tool import _normalize_mcp_input_schema
+
+        schema = _normalize_mcp_input_schema({
+            "type": None,
+            "properties": {"x": {"type": "integer"}},
+        })
+
+        assert schema["type"] == "object"
+
+    def test_required_pruned_when_property_missing(self):
+        """Gemini 400s on required names that don't exist in properties."""
+        from tools.mcp_tool import _normalize_mcp_input_schema
+
+        schema = _normalize_mcp_input_schema({
+            "type": "object",
+            "properties": {"a": {"type": "string"}},
+            "required": ["a", "ghost", "phantom"],
+        })
+
+        assert schema["required"] == ["a"]
+
+    def test_required_removed_when_all_names_dangle(self):
+        from tools.mcp_tool import _normalize_mcp_input_schema
+
+        schema = _normalize_mcp_input_schema({
+            "type": "object",
+            "properties": {},
+            "required": ["ghost"],
+        })
+
+        assert "required" not in schema
+
+    def test_required_pruning_applies_recursively_inside_nested_objects(self):
+        """Nested object schemas also get required pruning."""
+        from tools.mcp_tool import _normalize_mcp_input_schema
+
+        schema = _normalize_mcp_input_schema({
+            "type": "object",
+            "properties": {
+                "filter": {
+                    "type": "object",
+                    "properties": {"field": {"type": "string"}},
+                    "required": ["field", "missing"],
+                },
+            },
+        })
+
+        assert schema["properties"]["filter"]["required"] == ["field"]
+
+    def test_object_in_array_items_gets_properties_filled(self):
+        """Array-item object schemas without properties get an empty dict."""
+        from tools.mcp_tool import _normalize_mcp_input_schema
+
+        schema = _normalize_mcp_input_schema({
+            "type": "object",
+            "properties": {
+                "items": {
+                    "type": "array",
+                    "items": {"type": "object"},
+                },
+            },
+        })
+
+        assert schema["properties"]["items"]["items"]["properties"] == {}
+
+    def test_convert_mcp_schema_survives_missing_inputschema_attribute(self):
+        """A Tool object without .inputSchema must not crash registration."""
+        import types
+
+        from tools.mcp_tool import _convert_mcp_schema
+
+        bare_tool = types.SimpleNamespace(name="probe", description="Probe")
+        schema = _convert_mcp_schema("srv", bare_tool)
+
+        assert schema["name"] == "mcp_srv_probe"
+        assert schema["parameters"] == {"type": "object", "properties": {}}
+
+    def test_convert_mcp_schema_with_none_inputschema(self):
+        """Tool with inputSchema=None produces a valid empty object schema."""
+        import types
+
+        from tools.mcp_tool import _convert_mcp_schema
+
+        # Note: _make_mcp_tool(input_schema=None) falls back to a default —
+        # build the namespace directly so .inputSchema really is None.
+        mcp_tool = types.SimpleNamespace(name="probe", description="Probe", inputSchema=None)
+        schema = _convert_mcp_schema("srv", mcp_tool)
+
+        assert schema["parameters"] == {"type": "object", "properties": {}}
+
     def test_tool_name_prefix_format(self):
         from tools.mcp_tool import _convert_mcp_schema
 

tools/mcp_tool.py

@@ -2026,6 +2026,19 @@ def _normalize_mcp_input_schema(schema: dict | None) -> dict:
     requires local refs to point into ``#/$defs/...`` instead.  Normalize the
     common draft-07 shape here so MCP tool schemas remain portable across
     OpenAI-compatible providers.
+
+    Additional MCP-server robustness repairs applied recursively:
+
+    * Missing or ``null`` ``type`` on an object-shaped node is coerced to
+      ``"object"`` (some servers omit it).  See PR #4897.
+    * When an ``object`` node lacks ``properties``, an empty ``properties``
+      dict is added so ``required`` entries don't dangle.
+    * ``required`` arrays are pruned to only names that exist in
+      ``properties``; otherwise Google AI Studio / Gemini 400s with
+      ``property is not defined``.  See PR #4651.
+
+    All repairs are provider-agnostic and ideally produce a schema valid on
+    OpenAI, Anthropic, Gemini, and Moonshot in one pass.
     """
     if not schema:
         return {"type": "object", "properties": {}}
@@ -2044,10 +2057,52 @@ def _normalize_mcp_input_schema(schema: dict | None) -> dict:
             return [_rewrite_local_refs(item) for item in node]
         return node
 
-    normalized = _rewrite_local_refs(schema)
+    def _repair_object_shape(node):
+        """Recursively repair object-shaped nodes: fill type, prune required."""
+        if isinstance(node, list):
+            return [_repair_object_shape(item) for item in node]
+        if not isinstance(node, dict):
+            return node
 
+        repaired = {k: _repair_object_shape(v) for k, v in node.items()}
+
+        # Coerce missing / null type when the shape is clearly an object
+        # (has properties or required but no type).
+        if not repaired.get("type") and (
+            "properties" in repaired or "required" in repaired
+        ):
+            repaired["type"] = "object"
+
+        if repaired.get("type") == "object":
+            # Ensure properties exists so required can reference it safely
+            if "properties" not in repaired or not isinstance(
+                repaired.get("properties"), dict
+            ):
+                repaired["properties"] = {} if "properties" not in repaired else repaired["properties"]
+                if not isinstance(repaired.get("properties"), dict):
+                    repaired["properties"] = {}
+
+            # Prune required to only include names that exist in properties
+            required = repaired.get("required")
+            if isinstance(required, list):
+                props = repaired.get("properties") or {}
+                valid = [r for r in required if isinstance(r, str) and r in props]
+                if len(valid) != len(required):
+                    if valid:
+                        repaired["required"] = valid
+                    else:
+                        repaired.pop("required", None)
+
+        return repaired
+
+    normalized = _rewrite_local_refs(schema)
+    normalized = _repair_object_shape(normalized)
+
+    # Ensure top-level is a well-formed object schema
+    if not isinstance(normalized, dict):
+        return {"type": "object", "properties": {}}
     if normalized.get("type") == "object" and "properties" not in normalized:
-        return {**normalized, "properties": {}}
+        normalized = {**normalized, "properties": {}}
 
     return normalized
 
@@ -2080,7 +2135,7 @@ def _convert_mcp_schema(server_name: str, mcp_tool) -> dict:
     return {
         "name": prefixed_name,
         "description": mcp_tool.description or f"MCP tool {mcp_tool.name} from {server_name}",
-        "parameters": _normalize_mcp_input_schema(mcp_tool.inputSchema),
+        "parameters": _normalize_mcp_input_schema(getattr(mcp_tool, "inputSchema", None)),
     }