test(mcp): cover M.6 guard false path for ToolAnnotations

Author: SutuSebastian

src/application/mcp-tool-annotations.test.ts

@@ -3,9 +3,11 @@ import { describe, expect, it } from "bun:test";
 import { MCP_TOOL_NAMES } from "./mcp-tool-allowlist";
 import {
   MCP_TOOL_ANNOTATIONS,
+  _setSdkSupportsMcpToolAnnotationsForTests,
   buildHttpToolCatalogEntry,
   getMcpToolAnnotations,
   sdkSupportsMcpToolAnnotations,
+  withToolAnnotations,
 } from "./mcp-tool-annotations";
 
 describe("mcp-tool-annotations", () => {
@@ -46,6 +48,21 @@ describe("mcp-tool-annotations", () => {
     expect(sdkSupportsMcpToolAnnotations()).toBe(true);
   });
 
+  it("omits MCP annotations when M.6 guard is false", () => {
+    _setSdkSupportsMcpToolAnnotationsForTests(false);
+    try {
+      expect(getMcpToolAnnotations("apply")).toBeUndefined();
+      expect(
+        withToolAnnotations("apply", {
+          description: "test",
+          inputSchema: {},
+        }),
+      ).toEqual({ description: "test", inputSchema: {} });
+    } finally {
+      _setSdkSupportsMcpToolAnnotationsForTests(undefined);
+    }
+  });
+
   it("index user-data mutators are not destructive", () => {
     for (const name of [
       "save_baseline",

src/application/mcp-tool-annotations.ts

@@ -8,8 +8,20 @@ import type { ToolAnnotations } from "@modelcontextprotocol/sdk/types.js";
 
 import type { McpToolName } from "./mcp-tool-allowlist";
 
+let sdkSupportOverrideForTests: boolean | undefined;
+
+/** Test hook — restore with `undefined` in `afterEach`. */
+export function _setSdkSupportsMcpToolAnnotationsForTests(
+  value: boolean | undefined,
+): void {
+  sdkSupportOverrideForTests = value;
+}
+
 /** M.6 — skip MCP annotations when an older SDK lacks ToolAnnotations on registerTool. */
 export function sdkSupportsMcpToolAnnotations(): boolean {
+  if (sdkSupportOverrideForTests !== undefined) {
+    return sdkSupportOverrideForTests;
+  }
   const shape = ToolAnnotationsSchema?.shape;
   return (
     typeof shape === "object" &&
@@ -101,7 +113,7 @@ export function buildHttpToolCatalogEntry(name: McpToolName): {
   return { name, ...MCP_TOOL_ANNOTATIONS[name] };
 }
 
-export interface ToolRegisterConfig {
+interface ToolRegisterConfig {
   description: string;
   inputSchema: unknown;
 }