fix(core): strip additionalProperties from tool schemas

Author: MikeRyanDev

packages/core/src/core/__tests__/run-handler-schema.test.ts

@@ -0,0 +1,59 @@
+import { describe, expect, it } from "vitest";
+import { z } from "zod";
+import { RunHandler } from "../run-handler";
+import type { CopilotKitCore } from "../core";
+
+function createRunHandler(): RunHandler {
+  return new RunHandler({} as CopilotKitCore);
+}
+
+describe("RunHandler tool schema generation", () => {
+  it("strips boolean additionalProperties emitted by zod-to-json-schema", () => {
+    const runHandler = createRunHandler();
+    runHandler.initialize([
+      {
+        name: "sample",
+        parameters: z.object({
+          foo: z.string(),
+        }),
+      },
+    ]);
+
+    const [tool] = runHandler.buildFrontendTools();
+    expect(tool.parameters).toEqual({
+      type: "object",
+      properties: {
+        foo: { type: "string" },
+      },
+      required: ["foo"],
+    });
+  });
+
+  it("removes additionalProperties even for catchalls", () => {
+    const runHandler = createRunHandler();
+    runHandler.initialize([
+      {
+        name: "catchall",
+        parameters: z.object({}).catchall(z.string()),
+      },
+    ]);
+
+    const [tool] = runHandler.buildFrontendTools();
+    expect(tool.parameters).not.toHaveProperty("additionalProperties");
+  });
+
+  it("returns an empty schema for tools without parameters", () => {
+    const runHandler = createRunHandler();
+    runHandler.initialize([
+      {
+        name: "noSchema",
+      },
+    ]);
+
+    const [tool] = runHandler.buildFrontendTools();
+    expect(tool.parameters).toEqual({
+      type: "object",
+      properties: {},
+    });
+  });
+});

packages/core/src/core/run-handler.ts

@@ -550,15 +550,14 @@ export class RunHandler {
 const EMPTY_TOOL_SCHEMA = {
   type: "object",
   properties: {},
-  additionalProperties: false,
 } as const satisfies Record<string, unknown>;
 
 /**
  * Create a JSON schema from a tool's parameters
  */
 function createToolSchema(tool: FrontendTool<any>): Record<string, unknown> {
   if (!tool.parameters) {
-    return EMPTY_TOOL_SCHEMA;
+    return { ...EMPTY_TOOL_SCHEMA };
   }
 
   const rawSchema = zodToJsonSchema(tool.parameters, {
@@ -577,9 +576,28 @@ function createToolSchema(tool: FrontendTool<any>): Record<string, unknown> {
   if (typeof schema.properties !== "object" || schema.properties === null) {
     schema.properties = {};
   }
-  if (schema.additionalProperties === undefined) {
-    schema.additionalProperties = false;
-  }
 
+  stripAdditionalProperties(schema);
   return schema;
 }
+
+function stripAdditionalProperties(schema: unknown): void {
+  if (!schema || typeof schema !== "object") {
+    return;
+  }
+
+  if (Array.isArray(schema)) {
+    schema.forEach(stripAdditionalProperties);
+    return;
+  }
+
+  const record = schema as Record<string, unknown>;
+
+  if (record.additionalProperties !== undefined) {
+    delete record.additionalProperties;
+  }
+
+  for (const value of Object.values(record)) {
+    stripAdditionalProperties(value);
+  }
+}

packages/core/src/core/suggestion-engine.ts

@@ -434,11 +434,9 @@ const SUGGEST_TOOL: Tool = {
             },
           },
           required: ["title", "message"],
-          additionalProperties: false,
         },
       },
     },
     required: ["suggestions"],
-    additionalProperties: false,
   },
 };