Slack-Formatted Output Guide

This guide explains how to use the new Slack-formatted output feature in the Slack MCP Client.

Overview

The Slack MCP Client now supports rich message formatting using Slack's Block Kit and Markdown (mrkdwn) syntax. This allows for more visually appealing and interactive messages in Slack.

Features

1. Automatic Format Detection

The client automatically detects the format of messages and applies the appropriate formatting:

• Plain Text: Simple text messages

• Markdown Text: Messages with Markdown formatting (bold, italic, code blocks, etc.)

• JSON Block Kit: Messages in Block Kit JSON format

• Structured Data: Messages with key-value pairs that are automatically converted to Block Kit format

2. Markdown Formatting

You can use Slack's Markdown syntax in your messages. The formatter automatically converts standard Markdown syntax to Slack's mrkdwn format. For a comprehensive mapping between standard Markdown and Slack's supported syntax, see the Markdown-Slack Mapping Guide.

• Bold:

  • Standard Markdown: **bold text**

  • Slack Markdown: *bold text* (automatically converted)

• Italic:

  • Standard Markdown: *italic text* or _italic text_

  • Slack Markdown: _italic text_ (automatically converted)

• Strikethrough:

  • Standard Markdown: ~~struck text~~

  • Slack Markdown: ~struck text~ (automatically converted)

• Code: `code` (same in both)

• Code Block:

  ```language
  code block

• Block Quote:

  > This is a quote
  > Multi-line quote

• Lists:

  • Bullet item (or - Bullet item)
  • Another bullet item
  
  1. Numbered item
  2. Another numbered item

• Links:

  • Standard Markdown: [link text](https://example.com)

  • Slack Markdown: <https://example.com|link text> (automatically converted)

Automatic Quoted String Conversion

The formatter automatically converts double-quoted strings to inline code blocks for better visualization. For example:

All of these were created on "2020-11-17T05:07:52Z" or "2020-11-17T05:07:54Z".
Among them, "kube-node-lease", "kube-public", and "kube-system" share the exact
same creation timestamp: "2020-11-17T05:07:52Z".

Will be displayed as:

All of these were created on `2020-11-17T05:07:52Z` or `2020-11-17T05:07:54Z`.
Among them, `kube-node-lease`, `kube-public`, and `kube-system` share the exact
same creation timestamp: `2020-11-17T05:07:52Z`.

This makes timestamps, IDs, and other quoted values stand out better in messages.

3. Block Kit JSON

For more complex layouts, you can return a Block Kit JSON structure:

{
  "text": "Summary: Job completed",
  "blocks": [
    {
      "type": "header",
      "text": {
        "type": "plain_text",
        "text": "Job Status"
      }
    },
    {
      "type": "section",
      "fields": [
        {
          "type": "mrkdwn",
          "text": "*Result:*\nSuccess"
        },
        {
          "type": "mrkdwn",
          "text": "*Duration:*\n5m 32s"
        }
      ]
    },
    {
      "type": "section",
      "text": {
        "type": "mrkdwn",
        "text": "View logs: <http://logs.example.com|Open Logs>"
      }
    }
  ]
}

4. Structured Data

The client can automatically convert structured data (key-value pairs) to Block Kit format:

Status: Success
Duration: 5m 32s
Result: Passed

This will be displayed as a nicely formatted Block Kit message with fields.

Usage in Code

The formatter package provides several utility functions for formatting messages:

import "github.com/tuannvm/slack-mcp-client/internal/slack/formatter"

// Format text as bold
boldText := formatter.BoldText("Important")

// Create a code block
codeBlock := formatter.CodeBlock("var x = 10;", "javascript")

// Create a link
link := formatter.Link("http://example.com", "Example")

// Create a Block Kit message
blockOptions := formatter.BlockOptions{
    HeaderText: "Status Report",
    Fields: []formatter.Field{
        {Title: "Status", Value: "Success"},
        {Title: "Duration", Value: "5m 32s"},
    },
    Actions: []formatter.Action{
        {Text: "View Details", URL: "http://example.com"},
    },
}
blockMessage := formatter.CreateBlockMessage("Operation completed successfully", blockOptions)

Implementation Details

The Slack-formatted output feature is implemented in the internal/slack/formatter package, which provides:

1. Message Type Detection: Automatically detects the type of message (plain text, markdown, JSON Block Kit, structured data)

2. Formatting Functions: Utility functions for formatting text with Markdown

3. Block Kit Generation: Functions for creating Block Kit messages

4. Structured Data Conversion: Automatic conversion of structured data to Block Kit format

The postMessage method in the Slack client has been updated to use these formatting functions.

Examples

Example 1: Simple Markdown

*Build #123* _passed_ 🎉
• Duration: 4m 12s
• Triggered by: <@U23456789>

Example 2: Block Kit JSON

{
  "text": "Latest build results: Passed",
  "blocks": [
    {
      "type": "section",
      "text": {
        "type": "mrkdwn",
        "text": "*Build #123* _passed_ 🎉\n• Duration: 4m 12s\n• Triggered by: <@U23456789>"
      }
    },
    {
      "type": "actions",
      "elements": [
        {
          "type": "button",
          "text": {
            "type": "plain_text",
            "text": "View Details"
          },
          "url": "http://ci.example.com/build/123"
        }
      ]
    }
  ]
}

Example 3: Structured Data

Title: Build Status
Status: Success
Duration: 4m 12s
Triggered By: User123

This will be automatically converted to a Block Kit message with a header and fields.