Add RequestOptions.timeout

Author: jspahrsummers

src/shared/protocol.ts

@@ -37,6 +37,11 @@ export type ProtocolOptions = {
   enforceStrictCapabilities?: boolean;
 };
 
+/**
+ * The default request timeout, in miliseconds.
+ */
+export const DEFAULT_REQUEST_TIMEOUT_MSEC = 60000;
+
 /**
  * Options that can be given per request.
  */
@@ -50,6 +55,13 @@ export type RequestOptions = {
    * Can be used to cancel an in-flight request. This will cause an AbortError to be raised from request().
    */
   signal?: AbortSignal;
+
+  /**
+   * A timeout (in milliseconds) for this request. If exceeded, an McpError with code `RequestTimeout` will be raised from request().
+   *
+   * If not specified, `DEFAULT_REQUEST_TIMEOUT_MSEC` will be used as the timeout.
+   */
+  timeout?: number;
 };
 
 /**
@@ -379,7 +391,13 @@ export abstract class Protocol<
         };
       }
 
+      let timeoutId: ReturnType<typeof setTimeout> | undefined = undefined;
+
       this._responseHandlers.set(messageId, (response) => {
+        if (timeoutId !== undefined) {
+          clearTimeout(timeoutId);
+        }
+
         if (options?.signal?.aborted) {
           return;
         }
@@ -396,8 +414,7 @@ export abstract class Protocol<
         }
       });
 
-      options?.signal?.addEventListener("abort", () => {
-        const reason = options?.signal?.reason;
+      const cancel = (reason: unknown) => {
         this._responseHandlers.delete(messageId);
         this._progressHandlers.delete(messageId);
 
@@ -411,9 +428,34 @@ export abstract class Protocol<
         });
 
         reject(reason);
+      };
+
+      options?.signal?.addEventListener("abort", () => {
+        if (timeoutId !== undefined) {
+          clearTimeout(timeoutId);
+        }
+
+        cancel(options?.signal?.reason);
       });
 
-      this._transport.send(jsonrpcRequest).catch(reject);
+      const timeout = options?.timeout ?? DEFAULT_REQUEST_TIMEOUT_MSEC;
+      timeoutId = setTimeout(
+        () =>
+          cancel(
+            new McpError(ErrorCode.RequestTimeout, "Request timed out", {
+              timeout,
+            }),
+          ),
+        timeout,
+      );
+
+      this._transport.send(jsonrpcRequest).catch((error) => {
+        if (timeoutId !== undefined) {
+          clearTimeout(timeoutId);
+        }
+
+        reject(error);
+      });
     });
   }
 

src/types.ts

@@ -105,6 +105,7 @@ export const JSONRPCResponseSchema = z
 export enum ErrorCode {
   // SDK error codes
   ConnectionClosed = -1,
+  RequestTimeout = -2,
 
   // Standard JSON-RPC error codes
   ParseError = -32700,