Add ToolAnnotations support to McpServer.tool() method

src/types.ts

@@ -752,6 +752,62 @@ export const PromptListChangedNotificationSchema = NotificationSchema.extend({
 });
 
 /* Tools */
+/**
+ * Additional properties describing a Tool to clients.
+ * 
+ * NOTE: all properties in ToolAnnotations are **hints**. 
+ * They are not guaranteed to provide a faithful description of 
+ * tool behavior (including descriptive properties like `title`).
+ * 
+ * Clients should never make tool use decisions based on ToolAnnotations
+ * received from untrusted servers.
+ */
+export const ToolAnnotationsSchema = z
+  .object({
+    /**
+     * A human-readable title for the tool.
+     */
+    title: z.optional(z.string()),
+
+    /**
+     * If true, the tool does not modify its environment.
+     * 
+     * Default: false
+     */
+    readOnlyHint: z.optional(z.boolean()),
+
+    /**
+     * If true, the tool may perform destructive updates to its environment.
+     * If false, the tool performs only additive updates.
+     * 
+     * (This property is meaningful only when `readOnlyHint == false`)
+     * 
+     * Default: true
+     */
+    destructiveHint: z.optional(z.boolean()),
+
+    /**
+     * If true, calling the tool repeatedly with the same arguments 
+     * will have no additional effect on the its environment.
+     * 
+     * (This property is meaningful only when `readOnlyHint == false`)
+     * 
+     * Default: false
+     */
+    idempotentHint: z.optional(z.boolean()),
+
+    /**
+     * If true, this tool may interact with an "open world" of external
+     * entities. If false, the tool's domain of interaction is closed.
+     * For example, the world of a web search tool is open, whereas that
+     * of a memory tool is not.
+     * 
+     * Default: true
+     */
+    openWorldHint: z.optional(z.boolean()),
+  })
+  .passthrough();
+
 /**
  * Definition for a tool the client can call.
  */
@@ -774,6 +830,10 @@ export const ToolSchema = z
         properties: z.optional(z.object({}).passthrough()),
       })
       .passthrough(),
+    /**
+     * Optional additional tool information.
+     */
+    annotations: z.optional(ToolAnnotationsSchema),
   })
   .passthrough();
 
@@ -1246,6 +1306,7 @@ export type GetPromptResult = Infer<typeof GetPromptResultSchema>;
 export type PromptListChangedNotification = Infer<typeof PromptListChangedNotificationSchema>;
 
 /* Tools */
+export type ToolAnnotations = Infer<typeof ToolAnnotationsSchema>;
 export type Tool = Infer<typeof ToolSchema>;
 export type ListToolsRequest = Infer<typeof ListToolsRequestSchema>;
 export type ListToolsResult = Infer<typeof ListToolsResultSchema>;