From 798cc60f4c2c29c8edecc5584edba52085157294 Mon Sep 17 00:00:00 2001
From: liuhao1024 <sunsky.lau@gmail.com>
Date: Mon, 14 Sep 2026 11:56:34 +0800
Subject: [PATCH] fix(mcp): repair schema-map keywords per-entry in
 _repair_object_shape

_repair_object_shape recursed over every dict value as a schema node,
including the properties map itself. When one of the map's keys was
literally named properties/required, the missing-type heuristic fired on
the map and injected a bogus "type": "object" string as a parameter,
400ing the whole tool array on strict providers.

Recurse into map values only for the mapping-valued keywords
(properties, patternProperties, $defs, definitions, dependentSchemas),
matching the in-tree precedent in _rewrite_local_refs.

Fixes #110530
---
 tests/tools/test_mcp_tool.py | 59 ++++++++++++++++++++++++++++++++++++
 tools/mcp_tool_schema.py     | 15 ++++++++-
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/tests/tools/test_mcp_tool.py b/tests/tools/test_mcp_tool.py
index f9a333af52..9968026be9 100644
--- a/tests/tools/test_mcp_tool.py
+++ b/tests/tools/test_mcp_tool.py
@@ -518,6 +518,65 @@ class TestSchemaConversion:
         assert "definitions" not in schema["parameters"]
 
 
+    def test_properties_map_entry_named_properties_is_not_injected_with_type(self):
+        """A ``properties`` map must be repaired per-entry, never as a schema node.
+
+        Regression: ``_repair_object_shape`` recursed over every value as a
+        schema node, including the ``properties`` map itself. When one of its
+        KEYS was literally named ``properties``/``required``, the
+        missing-``type`` heuristic fired on the map and injected
+        ``"type": "object"`` — a bare string, not a schema — as a *parameter*.
+        Strict providers then 400 the whole tool array with
+        ``"object" is not of types "boolean", "object"``. Real-world repro: a
+        Tencent Docs MCP server whose ``smartsheet_add_table`` tool has a
+        parameter named ``properties`` (#110530).
+        """
+        from tools.mcp_tool_schema import _normalize_mcp_input_schema
+
+        normalized = _normalize_mcp_input_schema({
+            "type": "object",
+            "properties": {
+                "file_id": {"type": "string"},
+                "properties": {
+                    "type": "object",
+                    "properties": {"title": {"type": "string"}},
+                },
+            },
+        })
+
+        props = normalized["properties"]
+        # No bogus "type" parameter was injected into the properties map itself.
+        assert set(props) == {"file_id", "properties"}
+        # The legitimately-named `properties` parameter keeps its schema shape.
+        assert props["properties"]["type"] == "object"
+        assert props["properties"]["properties"] == {"title": {"type": "string"}}
+
+        # Same signature one level deeper (smartsheet add_view: items.properties map).
+        nested = _normalize_mcp_input_schema({
+            "type": "object",
+            "properties": {
+                "condition_items": {
+                    "type": "object",
+                    "properties": {
+                        "properties": {"type": "string"},
+                        "value": {"type": "string"},
+                    },
+                },
+            },
+        })
+        inner = nested["properties"]["condition_items"]["properties"]
+        assert set(inner) == {"properties", "value"}
+
+        # ``$defs`` is a schema map too: an entry literally named ``properties`` must not
+        # gain a bogus ``type`` sibling inside the ``$defs`` map.
+        defs_case = _normalize_mcp_input_schema({
+            "type": "object",
+            "properties": {"q": {"type": "string"}},
+            "$defs": {"properties": {"type": "string"}},
+        })
+        assert set(defs_case["$defs"]) == {"properties"}
+
+
     def test_optional_nullable_field_is_collapsed_to_non_null_schema(self):
         """Anthropic rejects MCP/Pydantic anyOf-null optional parameter schemas."""
         from tools.mcp_tool_schema import _normalize_mcp_input_schema
diff --git a/tools/mcp_tool_schema.py b/tools/mcp_tool_schema.py
index e0967b0126..8248047360 100644
--- a/tools/mcp_tool_schema.py
+++ b/tools/mcp_tool_schema.py
@@ -66,6 +66,11 @@ def _rewrite_local_refs(node):
     return normalized
 
 
+# Mapping-valued JSON Schema keywords: the value maps entry NAMES to schemas and is never a
+# schema node itself. Repair must recurse into the map's values only (#110530).
+_SCHEMA_MAP_KEYS = ("properties", "patternProperties", "$defs", "definitions", "dependentSchemas")
+
+
 def _repair_object_shape(node):
     """Recursively fill a missing object ``type``, ensure ``properties`` (so ``required``
     can't dangle) and prune ``required`` to names present in ``properties`` (Gemini 400s
@@ -74,7 +79,15 @@ def _repair_object_shape(node):
         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()}
+    repaired = {}
+    for key, value in node.items():
+        if key in _SCHEMA_MAP_KEYS and isinstance(value, dict):
+            # A schema map (entry name -> schema), never a schema node itself: recursing over
+            # the whole map would inject a bogus ``"type": "object"`` *entry* when one of its
+            # keys is literally named ``properties``/``required`` (#110530).
+            repaired[key] = {name: _repair_object_shape(schema) for name, schema in value.items()}
+        else:
+            repaired[key] = _repair_object_shape(value)
     if not repaired.get("type") and ("properties" in repaired or "required" in repaired):
         repaired["type"] = "object"
     if repaired.get("type") == "object":