slack-markdown-generator

name	slack-markdown-generator
description	Generate or convert any content into a Slack Block Kit JSON payload using markdown blocks, ready to paste into the Slack API or a webhook. Accepts freeform text, structured data (status updates, reports, meeting summaries), or existing standard markdown and handles Slack-specific quirks like the 12,000-character limit, image-to-link conversion, and flat header rendering. Use this skill whenever the user says "format this for Slack", "create a Slack message", "convert to Slack markdown", "generate a Slack notification", "make this Slack-ready", "write a Slack announcement", or mentions Slack messages, Slack Block Kit, Slack webhooks, or Slack markdown — even if they just paste content and say "send this to Slack" or "post this in our channel".
argument-hint	text, notes, data, or markdown to convert

Slack Markdown Message Generator

Turn any input into a Slack Block Kit JSON payload — ready to send via the Slack API, an incoming webhook, or the Block Kit Builder.

When this skill fits

Use it for requests like:

• "format this status update for Slack"
• "convert my release notes to a Slack message"
• "turn these meeting notes into a Slack post"
• "create a Slack Block Kit payload from this markdown file"
• "make this announcement Slack-ready"
• "I want to post this in our team channel"

Do not use it for:

• Sending messages directly to Slack (this skill generates the payload; it does not call the Slack API)
• Rich interactive messages with buttons, select menus, or input blocks (this skill targets markdown blocks only)
• Slack mrkdwn format (the legacy *bold*, _italic_ style) — this skill targets the newer markdown block type

Inputs

The user may provide any combination of:

• Freeform text — a casual description, announcement, or notes
• Structured data — key/value pairs, a status template, a table of items
• Existing markdown — a .md file or pasted standard markdown content

If no input is provided, ask the user to supply content before proceeding. If the intent is ambiguous (e.g. just "make a Slack message" with nothing else), ask one focused clarifying question — what content should go in the message?

Workflow

1. Understand the content

Read the input and identify its type:

• Freeform text: interpret the intent and shape the content into a clear, readable message
• Structured data: organise the fields into logical sections using headings, bold labels, and lists
• Existing markdown: preserve the structure as closely as possible, applying only the changes needed for Slack compatibility

If the content is long or multi-topic, plan to split it into multiple markdown blocks (see the character limit rule below).

2. Convert to Slack-compatible markdown

Before writing the output, read references/slack-markdown-spec.md. It contains the full syntax reference and gotchas. Key things to apply:

• Images (![alt](url)) are not rendered as images in Slack — convert them to hyperlinks [alt](url) or plain URLs
• Header levels all render at the same visual size in Slack. If the original uses heading hierarchy for visual structure, consider replacing deeper headings with bold labels or divider blocks to create separation
• 12,000-character limit: the cumulative text across all markdown blocks in a single payload must not exceed 12,000 characters. If the content is long, split it naturally at section boundaries into multiple blocks
• Unsupported HTML — remove or convert any raw HTML tags; Slack's markdown block does not render HTML

3. Build the Block Kit payload

Wrap the converted content in the standard Block Kit structure:

{
  "blocks": [
    {
      "type": "markdown",
      "text": "...your converted content..."
    }
  ]
}

Rules for the blocks array:

• Each section of content that is logically separate should be its own markdown block
• If you split for the character limit, each chunk becomes its own block
• Keep block_id out of markdown blocks — it is silently ignored by Slack
• If there is a clear title or header at the top, it can be its own short block for visual clarity

4. Output

Write the payload to a file named slack-message.json in the current working directory (or a path the user specifies).

After writing the file, show a brief preview in the response:

1. The file path
2. How many blocks the payload contains
3. The first ~300 characters of the first block's text field so the user can verify the content looks right
4. A note about any conversions made (images converted, headers flattened, content split, etc.)

Hard rules

• Never fabricate content not present in the input
• Never produce a block whose text exceeds 12,000 characters
• Never include raw ![...](...) image syntax in the output — always convert to a link
• If any conversion changes the meaning or drops content, call it out explicitly in your response