feat: add mcp client instruction support

src/types.ts

@@ -304,6 +304,12 @@ export const InitializeResultSchema = ResultSchema.extend({
   protocolVersion: z.string(),
   capabilities: ServerCapabilitiesSchema,
   serverInfo: ImplementationSchema,
+  /**
+   * Instructions describing how to use the server and its features.
+   *
+   * This can be used by clients to improve the LLM's understanding of available tools, resources, etc. It can be thought of like a "hint" to the model. For example, this information MAY be added to the system prompt.
+   */
+  instructions: z.optional(z.string()),
 });
 
 /**