feat: add optional instructions field to server _oninitialize

src/server/index.ts

@@ -33,6 +33,11 @@ export type ServerOptions = ProtocolOptions & {
    * Capabilities to advertise as being supported by this server.
    */
   capabilities: ServerCapabilities;
+
+  /**
+   * Optional instructions describing how to use the server and its features.
+   */
+  instructions?: string;
 };
 
 /**
@@ -72,6 +77,7 @@ export class Server<
   private _clientCapabilities?: ClientCapabilities;
   private _clientVersion?: Implementation;
   private _capabilities: ServerCapabilities;
+  private _instructions?: string;
 
   /**
    * Callback for when initialization has fully completed (i.e., the client has sent an `initialized` notification).
@@ -87,6 +93,7 @@ export class Server<
   ) {
     super(options);
     this._capabilities = options.capabilities;
+    this._instructions = options.instructions;
 
     this.setRequestHandler(InitializeRequestSchema, (request) =>
       this._oninitialize(request),
@@ -234,6 +241,7 @@ export class Server<
         : LATEST_PROTOCOL_VERSION,
       capabilities: this.getCapabilities(),
       serverInfo: this._serverInfo,
+      ...(this.getInstructions() && { instructions: this.getInstructions() }),
     };
   }
 
@@ -255,6 +263,10 @@ export class Server<
     return this._capabilities;
   }
 
+  private getInstructions(): string | undefined {
+    return this._instructions;
+  }
+
   async ping() {
     return this.request({ method: "ping" }, EmptyResultSchema);
   }