Gmail MCP Server

Instructions

Implementation Reference

• src/index.ts:357-372 (registration)

  Registration of the 'send_draft' tool using McpServer.tool(), including description, input schema, and the inline handler function that sends a draft using the Gmail API.
  server.tool("send_draft", "Send an existing draft", { id: z.string().describe("The ID of the draft to send") }, async (params) => { return handleTool(config, async (gmail: gmail_v1.Gmail) => { try { const { data } = await gmail.users.drafts.send({ userId: 'me', requestBody: { id: params.id } }) return formatResponse(data) } catch (error) { return formatResponse({ error: 'Error sending draft, are you sure you have at least one recipient?' }) } }) } )
• src/index.ts:359-361 (schema)

  Input schema for the 'send_draft' tool, defining the required 'id' parameter as a string.
  { id: z.string().describe("The ID of the draft to send") },
• src/index.ts:362-371 (handler)

  Handler function for executing the 'send_draft' tool logic. It uses handleTool to authenticate and call gmail.users.drafts.send with the provided draft ID, formatting the response or error.
  async (params) => { return handleTool(config, async (gmail: gmail_v1.Gmail) => { try { const { data } = await gmail.users.drafts.send({ userId: 'me', requestBody: { id: params.id } }) return formatResponse(data) } catch (error) { return formatResponse({ error: 'Error sending draft, are you sure you have at least one recipient?' }) } }) }
• src/index.ts:50-66 (helper)

  Shared helper function 'handleTool' used by 'send_draft' and other tools to handle OAuth2 authentication, Gmail client creation, and API call execution with error handling.
  const handleTool = async (queryConfig: Record<string, any> | undefined, apiCall: (gmail: gmail_v1.Gmail) => Promise<any>) => { try { const oauth2Client = queryConfig ? createOAuth2Client(queryConfig) : defaultOAuth2Client if (!oauth2Client) throw new Error('OAuth2 client could not be created, please check your credentials') const credentialsAreValid = await validateCredentials(oauth2Client) if (!credentialsAreValid) throw new Error('OAuth2 credentials are invalid, please re-authenticate') const gmailClient = queryConfig ? google.gmail({ version: 'v1', auth: oauth2Client }) : defaultGmailClient if (!gmailClient) throw new Error('Gmail client could not be created, please check your credentials') const result = await apiCall(gmailClient) return result } catch (error: any) { return `Tool execution failed: ${error.message}` } }
• src/index.ts:48-49 (helper)

  Helper function 'formatResponse' used to standardize tool responses into MCP content format by JSON stringifying the API response.
  const formatResponse = (response: any) => ({ content: [{ type: "text", text: JSON.stringify(response) }] })