fix(cert-11): harden MCP integration contract

certifications/claude/lessons/11-mcp-server-design-and-integration/code/main.py

@@ -53,7 +53,9 @@ class Capability:
             if name not in properties:
                 continue
             expected = properties[name].get("type")
-            if expected not in checks or not checks[expected](value):
+            if expected not in checks:
+                raise ValueError(f"unsupported schema type for {name}: {expected!r}")
+            if not checks[expected](value):
                 raise ValueError(f"{name} must be {expected}")
         return arguments
 
@@ -332,7 +334,6 @@ class MCPServer:
             },
         }
         capabilities = metadata[CLIENT_CAPABILITIES_KEY]
-        required = {"roots": {}, "sampling": {}, "elicitation": {"form": {}}}
         missing: dict[str, Any] = {}
         if not isinstance(capabilities.get("roots"), dict):
             missing["roots"] = {}

certifications/claude/lessons/11-mcp-server-design-and-integration/code/tests/test_main.py

@@ -10,6 +10,7 @@ sys.path.insert(0, str(pathlib.Path(__file__).parents[1]))
 from main import (
     CLIENT_CAPABILITIES_KEY,
     CLIENT_INFO_KEY,
+    Capability,
     CURRENT_PROTOCOL_VERSION,
     MCPClient,
     MCPServer,
@@ -119,6 +120,19 @@ class MCPTests(unittest.TestCase):
         )
         self.assertEqual(response["error"]["code"], -32602)
 
+    def test_capability_rejects_missing_and_unsupported_schema_types_explicitly(self):
+        for declared_type in (None, "number"):
+            with self.subTest(declared_type=declared_type):
+                schema = {"properties": {"topic": {}}}
+                if declared_type is not None:
+                    schema["properties"]["topic"]["type"] = declared_type
+                capability = Capability("review", "Review a topic.", schema, lambda args: args)
+                with self.assertRaisesRegex(
+                    ValueError,
+                    rf"unsupported schema type for topic: {declared_type!r}",
+                ):
+                    capability.validate_arguments({"topic": "release"})
+
     def test_resource_and_prompt_results_are_complete(self):
         listed = self.client.request("resources/list")
         read = self.client.request("resources/read", {"uri": listed["resources"][0]["uri"]})

certifications/claude/lessons/11-mcp-server-design-and-integration/docs/en.md

@@ -12,8 +12,7 @@
 - Explain the separate responsibilities of MCP host, client, and server
 - Build the MCP `2026-07-28` per-request metadata envelope
 - Implement mandatory `server/discover`, complete results, and cache hints
-- Use Multi Round-Trip Requests for roots, sampling, and elicitation compatibility
-- Explain why Roots, Sampling, and Logging are deprecated for new designs
+- Use Multi Round-Trip Requests for roots, sampling, and elicitation compatibility; explain why roots, sampling, and logging are deprecated for new designs
 - Deploy current Streamable HTTP without protocol sessions or sticky routing
 - Apply authorization, consent, integrity, and untrusted-output controls