feat(sequential-thinking): add tool annotations (#3534)

feat(sequential-thinking): add tool annotations

Adds MCP ToolAnnotations (readOnlyHint, destructiveHint, idempotentHint, openWorldHint) to the sequential-thinking tool, bringing it in line with the annotation pattern established by the filesystem server.

Fixes #3403

Author: nielskaspers

src/sequentialthinking/index.ts

@@ -81,6 +81,12 @@ You should:
       branchId: z.string().optional().describe("Branch identifier"),
       needsMoreThoughts: z.boolean().optional().describe("If more thoughts are needed")
     },
+    annotations: {
+      readOnlyHint: true,
+      destructiveHint: false,
+      idempotentHint: true,
+      openWorldHint: false,
+    },
     outputSchema: {
       thoughtNumber: z.number(),
       totalThoughts: z.number(),