list_threads

Instructions

Implementation Reference

• src/index.ts:753-787 (registration)

  The 'list_threads' tool is registered on the MCP server via server.tool() with the name 'list_threads', a description, Zod schema for parameters, and an async handler function.

  server.tool("list_threads",
    "List threads in the user's mailbox",
    {
      maxResults: z.number().optional().describe("Maximum number of threads to return"),
      pageToken: z.string().optional().describe("Page token to retrieve a specific page of results"),
      q: z.string().optional().describe("Only return threads matching the specified query"),
      labelIds: z.array(z.string()).optional().describe("Only return threads with labels that match all of the specified label IDs"),
      includeSpamTrash: z.boolean().optional().describe("Include threads from SPAM and TRASH in the results"),
      includeBodyHtml: z.boolean().optional().describe("Whether to include the parsed HTML in the return for each body, excluded by default because they can be excessively large"),
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.threads.list({ userId: 'me', ...params })
  
        if (data.threads) {
          data.threads = data.threads.map(thread => {
            if (thread.messages) {
              thread.messages = thread.messages.map(message => {
                if (message.payload) {
                  message.payload = processMessagePart(
                    message.payload,
                    params.includeBodyHtml
                  )
                }
                return message
              })
            }
            return thread
          })
        }
  
        return formatResponse(data)
      })
    }
  )

• src/index.ts:763-787 (handler)

  The handler function for 'list_threads' calls handleTool with a callback that invokes gmail.users.threads.list() with the provided parameters, then maps over the results to process message parts (optionally including HTML body) and returns the formatted response.

    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.threads.list({ userId: 'me', ...params })
  
        if (data.threads) {
          data.threads = data.threads.map(thread => {
            if (thread.messages) {
              thread.messages = thread.messages.map(message => {
                if (message.payload) {
                  message.payload = processMessagePart(
                    message.payload,
                    params.includeBodyHtml
                  )
                }
                return message
              })
            }
            return thread
          })
        }
  
        return formatResponse(data)
      })
    }
  )

• src/index.ts:755-762 (schema)

  The Zod input schema for list_threads defines optional parameters: maxResults (number), pageToken (string), q (string query), labelIds (array of strings), includeSpamTrash (boolean), and includeBodyHtml (boolean).

  {
    maxResults: z.number().optional().describe("Maximum number of threads to return"),
    pageToken: z.string().optional().describe("Page token to retrieve a specific page of results"),
    q: z.string().optional().describe("Only return threads matching the specified query"),
    labelIds: z.array(z.string()).optional().describe("Only return threads with labels that match all of the specified label IDs"),
    includeSpamTrash: z.boolean().optional().describe("Include threads from SPAM and TRASH in the results"),
    includeBodyHtml: z.boolean().optional().describe("Whether to include the parsed HTML in the return for each body, excluded by default because they can be excessively large"),
  },

• src/index.ts:50-80 (helper)

  The handleTool helper function wraps the Gmail API call with OAuth2 credential validation and error handling, used by the list_threads handler.

  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) {
      // Check for specific authentication errors
      if (
        error.message?.includes("invalid_grant") ||
        error.message?.includes("refresh_token") ||
        error.message?.includes("invalid_client") ||
        error.message?.includes("unauthorized_client") ||
        error.code === 401 ||
        error.code === 403
      ) {
        return formatResponse({
          error: `Authentication failed: ${error.message}. Please re-authenticate by running: npx @shinzolabs/gmail-mcp auth`,
        });
      }
  
      return formatResponse({ error: `Tool execution failed: ${error.message}` });
    }
  }