Slack MCP Server

Instructions

Implementation Reference

• src/index.ts:252-269 (handler)

  The handler implementation that parses input arguments, calls Slack's conversations.history API to fetch channel messages, validates the response, and returns the formatted result.

  case 'slack_get_channel_history': {
    const args = GetChannelHistoryRequestSchema.parse(
      request.params.arguments
    );
    const response = await slackClient.conversations.history({
      channel: args.channel_id,
      limit: args.limit,
      cursor: args.cursor,
    });
    if (!response.ok) {
      throw new Error(`Failed to get channel history: ${response.error}`);
    }
    const parsedResponse =
      ConversationsHistoryResponseSchema.parse(response);
    return {
      content: [{ type: 'text', text: JSON.stringify(parsedResponse) }],
    };
  }

• src/schemas.ts:116-134 (schema)

  Zod schema defining the input parameters for the slack_get_channel_history tool, including channel_id, optional cursor for pagination, and optional limit.

  export const GetChannelHistoryRequestSchema = z.object({
    channel_id: z
      .string()
      .describe(
        'The ID of the channel. Use this tool for: browsing latest messages without filters, getting ALL messages including bot/automation messages, sequential pagination. If you need to search by user, keywords, or dates, use slack_search_messages instead.'
      ),
    cursor: z
      .string()
      .optional()
      .describe('Pagination cursor for next page of results'),
    limit: z
      .number()
      .int()
      .min(1)
      .max(1000) // Align with Slack API's default limit
      .optional()
      .default(100) // The reference repository uses 10, but aligning with list_channels etc., set to 100
      .describe('Number of messages to retrieve (default 100)'),
  });

• src/index.ts:136-141 (registration)

  Registration of the slack_get_channel_history tool in the listTools response, including name, detailed description, and reference to the input schema.

  {
    name: 'slack_get_channel_history',
    description:
      'Get messages from a channel in chronological order. Use this when: 1) You need the latest conversation flow without specific filters, 2) You want ALL messages including bot/automation messages, 3) You need to browse messages sequentially with pagination. Do NOT use if you have specific search criteria (user, keywords, dates) - use slack_search_messages instead.',
    inputSchema: zodToJsonSchema(GetChannelHistoryRequestSchema),
  },