modify_message

Instructions

Implementation Reference

• src/index.ts:625-638 (registration)

  The 'modify_message' tool is registered via server.tool() on the McpServer. The registration includes both the schema definition (input parameters: id, addLabelIds, removeLabelIds) and the handler function.

  server.tool("modify_message",
    "Modify the labels on a message",
    {
      id: z.string().describe("The ID of the message to modify"),
      addLabelIds: z.array(z.string()).optional().describe("A list of label IDs to add to the message"),
      removeLabelIds: z.array(z.string()).optional().describe("A list of label IDs to remove from the message")
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.messages.modify({ userId: 'me', id: params.id, requestBody: { addLabelIds: params.addLabelIds, removeLabelIds: params.removeLabelIds } })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:627-631 (schema)

  Input schema for modify_message: requires 'id' (string), and optional 'addLabelIds' and 'removeLabelIds' (arrays of strings).

  {
    id: z.string().describe("The ID of the message to modify"),
    addLabelIds: z.array(z.string()).optional().describe("A list of label IDs to add to the message"),
    removeLabelIds: z.array(z.string()).optional().describe("A list of label IDs to remove from the message")
  },

• src/index.ts:632-638 (handler)

  Handler function: validates credentials via handleTool, then calls the Gmail API's users.messages.modify() to add/remove labels on the specified message.

    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.messages.modify({ userId: 'me', id: params.id, requestBody: { addLabelIds: params.addLabelIds, removeLabelIds: params.removeLabelIds } })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:50-80 (helper)

  The handleTool helper wraps all tool handlers. It creates/reuses OAuth2 credentials, validates them, and executes the provided API call, with error handling for auth failures.

  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}` });
    }
  }