Slack MCP Server

Instructions

Implementation Reference

• src/tools/channels.ts:9-25 (handler)

  The main handler function that implements the 'list_channels' tool logic. It validates input with Zod schema and calls Slack's conversations.list API, returning channels and pagination cursor.

  export async function listChannels(client: SlackClientWrapper, args: unknown) {
    const params = listChannelsSchema.parse(args);
  
    return await client.safeCall(async () => {
      const result = await client.getClient().conversations.list({
        types: params.types,
        exclude_archived: params.exclude_archived,
        limit: params.limit,
        cursor: params.cursor,
      });
  
      return {
        channels: result.channels || [],
        next_cursor: result.response_metadata?.next_cursor,
      };
    });
  }

• src/utils/validators.ts:11-16 (schema)

  Zod schema used for input validation in the listChannels handler.

  export const listChannelsSchema = z.object({
    types: z.string().optional().default('public_channel,private_channel'),
    exclude_archived: z.boolean().optional().default(true),
    limit: z.number().min(1).max(1000).optional().default(100),
    cursor: z.string().optional(),
  });

• src/index.ts:47-72 (registration)

  Tool definition registration in the list_tools response, including name, description, and input schema.

  {
    name: 'list_channels',
    description: 'List channels in the Slack workspace',
    inputSchema: {
      type: 'object',
      properties: {
        types: {
          type: 'string',
          description: 'Comma-separated list of channel types (public_channel, private_channel, mpim, im)',
          default: 'public_channel,private_channel',
        },
        exclude_archived: {
          type: 'boolean',
          description: 'Exclude archived channels',
          default: true,
        },
        limit: {
          type: 'number',
          description: 'Maximum number of channels to return',
          default: 100,
          minimum: 1,
          maximum: 1000,
        },
      },
    },
  },

• src/index.ts:415-415 (registration)

  Handler registration in the toolHandlers map for the call_tool request, linking 'list_channels' to the imported listChannels function.

  list_channels: (args) => channelTools.listChannels(slackClient, args),