Alchemy MCP Plugin

Instructions

Implementation Reference

• index.ts:1089-1135 (handler)

  Handler function for the 'subscribe' tool. Validates parameters, creates an Alchemy WebSocket subscription based on the type ('newHeads', 'logs', 'pendingTransactions', 'mined'), stores the subscription with a generated ID, and returns the subscriptionId.
  private async handleSubscribe(args: Record<string, unknown>) { const params = this.validateAndCastParams<SubscribeParams>( args, isValidSubscribeParams, "Invalid subscribe parameters" ); const subscriptionId = Math.random().toString(36).substring(7); let subscription; switch (params.type) { case "newHeads": subscription = this.alchemy.ws.on("block", (blockNumber) => { console.log("[WebSocket] New block:", blockNumber); }); break; case "logs": subscription = this.alchemy.ws.on( { address: params.address, topics: params.topics, }, (log) => { console.log("[WebSocket] New log:", log); } ); break; case "pendingTransactions": subscription = this.alchemy.ws.on("pending", (tx) => { console.log("[WebSocket] Pending transaction:", tx); }); break; case "mined": subscription = this.alchemy.ws.on("mined", (tx) => { console.log("[WebSocket] Mined transaction:", tx); }); break; default: throw new McpError( ErrorCode.InvalidParams, `Unknown subscription type: ${params.type}` ); } this.activeSubscriptions.set(subscriptionId, subscription); return { subscriptionId }; }
• index.ts:936-961 (registration)

  Registration of the 'subscribe' tool in the ListTools response, including name, description, and inputSchema.
  { name: "subscribe", description: "Subscribe to blockchain events", inputSchema: { type: "object", properties: { type: { type: "string", enum: ["newHeads", "logs", "pendingTransactions", "mined"], description: "The type of subscription", }, address: { type: "string", description: "The address to filter by (for logs)", }, topics: { type: "array", items: { type: "string", }, description: "The topics to filter by (for logs)", }, }, required: ["type"], }, },
• index.ts:93-97 (schema)

  Type definition for SubscribeParams used in the handler for input validation.
  type SubscribeParams = { type: string; address?: string; topics?: string[]; };
• index.ts:1054-1065 (helper)

  Validation helper function isValidSubscribeParams used to validate subscribe parameters before casting.
  isValidSubscribeParams = (args: any): args is SubscribeParams => { return ( typeof args === "object" && args !== null && typeof args.type === "string" && ["newHeads", "logs", "pendingTransactions", "mined"].includes( args.type ) && (args.address === undefined || typeof args.address === "string") && (args.topics === undefined || Array.isArray(args.topics)) ); };
• index.ts:999-1001 (registration)

  Dispatcher switch case that routes 'subscribe' tool calls to the handleSubscribe handler.
  case "subscribe": result = await this.handleSubscribe(request.params.arguments); break;