Retell AI MCP Server

Instructions

Implementation Reference

• src/index.ts:1171-1172 (handler)

  The handler logic for the 'retell_get_agent' tool within the executeTool switch statement. It constructs the API endpoint using the agent_id from input args and calls the retellRequest helper.

  case "retell_get_agent":
    return retellRequest(`/get-agent/${args.agent_id}`, "GET");

• src/index.ts:504-517 (schema)

  The tool schema definition including name, description, and inputSchema for validating the agent_id parameter.

  {
    name: "retell_get_agent",
    description: "Retrieve the configuration and details of a specific voice agent.",
    inputSchema: {
      type: "object",
      properties: {
        agent_id: {
          type: "string",
          description: "The unique identifier of the agent"
        }
      },
      required: ["agent_id"]
    }
  },

• src/index.ts:1283-1285 (registration)

  Registration of the tool listing handler that exposes all tools, including 'retell_get_agent', via the MCP protocol.

  server.setRequestHandler(ListToolsRequestSchema, async () => {
    return { tools };
  });

• src/index.ts:23-57 (helper)

  Core HTTP client helper function that performs authenticated API requests to Retell AI backend, used by all tool handlers including retell_get_agent.

  async function retellRequest(
    endpoint: string,
    method: string = "GET",
    body?: Record<string, unknown>
  ): Promise<unknown> {
    const apiKey = getApiKey();
  
    const headers: Record<string, string> = {
      "Authorization": `Bearer ${apiKey}`,
      "Content-Type": "application/json",
    };
  
    const options: RequestInit = {
      method,
      headers,
    };
  
    if (body && method !== "GET") {
      options.body = JSON.stringify(body);
    }
  
    const response = await fetch(`${RETELL_API_BASE}${endpoint}`, options);
  
    if (!response.ok) {
      const errorText = await response.text();
      throw new Error(`Retell API error (${response.status}): ${errorText}`);
    }
  
    // Handle 204 No Content
    if (response.status === 204) {
      return { success: true };
    }
  
    return response.json();
  }

• src/index.ts:1288-1293 (registration)

  MCP server request handler for tool execution, which dispatches to executeTool based on tool name, enabling 'retell_get_agent' execution.

  server.setRequestHandler(CallToolRequestSchema, async (request) => {
    const { name, arguments: args } = request.params;
  
    try {
      const result = await executeTool(name, args as Record<string, unknown>);
      return {