fix(mcp): align runtime unknown argument validation

src/server/toolInputValidation.ts

@@ -6,6 +6,7 @@ import {
 } from "../domain/errors.js";
 import { projectInputIssues } from "../domain/inputIssueProjection.js";
 import { err, ok, type Result } from "../domain/result.js";
+import { closeObjectSchemas } from "./toolRegistrationOptions.js";
 
 /** Parse one MCP request exactly once and retain only schema-owned correction data. */
 export const safeParseToolInput = <Schema extends z.ZodType>(
@@ -41,7 +42,7 @@ const unknownArgumentIssues = (
       throw new TypeError(
         "Tool input schema does not expose Standard JSON Schema",
       );
-    jsonSchema = converter({ target: "draft-2020-12" });
+    jsonSchema = closeObjectSchemas(converter({ target: "draft-2020-12" }));
     schemaCache.set(schema, jsonSchema);
   }
   return scanUnknownArguments(input, jsonSchema, jsonSchema, []);

src/server/toolRegistrationOptions.ts

@@ -67,7 +67,8 @@ const inputJsonSchema = (schema: z.ZodObject): Record<string, unknown> => {
   return converter({ target: "draft-2020-12" });
 };
 
-const closeObjectSchemas = (
+/** Close fixed-shape JSON Schema objects while preserving explicit maps. */
+export const closeObjectSchemas = (
   value: Readonly<Record<string, unknown>>,
 ): Record<string, unknown> => {
   const closed = Object.fromEntries(

tests/enhancedTools.test.ts

@@ -629,6 +629,28 @@ describe("enhanced MCP tools", () => {
         },
       },
     });
+    const nestedMisspelled = await client.callTool({
+      name: "analyze_function",
+      arguments: {
+        procedure: "0x1",
+        collection_offset: { commentz: 1 },
+      },
+    });
+    expect(nestedMisspelled).toMatchObject({
+      isError: true,
+      structuredContent: {
+        error: {
+          details: {
+            issues: [
+              {
+                path: ["collection_offset", "commentz"],
+                reason: "unknown_argument",
+              },
+            ],
+          },
+        },
+      },
+    });
     const bounded = await client.callTool({
       name: "trace_feature",
       arguments: { query: "needle", max_operations: 101 },