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slack-formatting

Formats agent output for Slack delivery using mrkdwn text and Block Kit JSON blocks.

1|Updated Jun 21, 2026
Search Tags:#slack#file upload#threading#mrkdwn#block kit#message formatting#chat.postmessage
One-click install
npx skills add https://github.com/tapway/shogun-os --skill slack-formatting-tapway
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: slack-formatting
Source: https://github.com/tapway/shogun-os/tree/main/skills/communication/slack-formatting
Command: npx skills add https://github.com/tapway/shogun-os --skill slack-formatting-tapway

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Slack messages often render poorly when agents output raw markdown: pipe tables appear as literal text, long messages get truncated mid-sentence, and file uploads fail against deprecated APIs. This Skill defines the exact formatting rules and delivery patterns for producing correctly rendered Slack messages. ## Core Features & Use Cases - Dual delivery modes: mrkdwn text for simple messages via send_message, and Block Kit JSON (header, section, table, alert, card, actions, markdown blocks) for rich layouts via chat.postMessage. - Gateway Block Kit pass-through: output a JSON payload with a top-level blocks array and the gateway auto-detects and renders it as native Slack blocks. - Long-content threading: split long reports into threaded messages of 2-3 section blocks each to avoid the 3,000-character mrkdwn truncation limit. - File uploads: the 3-step files.getUploadURLExternal flow with form-encoded bodies, replacing the deprecated files.upload API. - Use Case: An agent generating a daily project digest outputs Block Kit JSON with a header, status summary section, a markdown table of projects, and a context footer, which the gateway renders as a rich Slack message. ## Quick Start Format my project status report as a Slack Block Kit message with a header, summary section, and a table of active projects.

Frequently Asked Questions about slack-formatting

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I send a table in a Slack message?▼

Slack mrkdwn does not render pipe tables, so output Block Kit JSON with a markdown block containing the pipe table, or use a table block with raw_text cells. The gateway detects the JSON blocks array and renders it as a proper table.

What is the difference between mrkdwn and Block Kit in Slack?▼

Mrkdwn is Slack's lightweight text syntax for simple messages sent via send_message, supporting bold, italic, links, and lists. Block Kit is a JSON framework of blocks like header, section, table, and alert for rich structured layouts sent via chat.postMessage.

Why do my pipe tables render as raw text in Slack?▼

Slack mrkdwn has no table support, so pipe syntax displays as literal characters. Wrap the table in a Block Kit markdown block inside a JSON blocks array, which the gateway passes through to Slack for correct rendering.

How do I upload a file to Slack with the API?▼

Use the 3-step flow: call files.getUploadURLExternal with form-encoded data, POST the raw bytes to the returned URL, then call files.completeUploadExternal with the channel_id. The old files.upload method is deprecated and returns method_deprecated.

Why is my long Slack message getting cut off?▼

Slack truncates mrkdwn text fields at 3,000 characters and limits messages to 50 blocks. Split long content into multiple threaded messages with 2-3 section blocks each, keeping each section under roughly 2,500 characters.

Can I use markdown links and headers in Slack messages?▼

No. Slack does not support [text](url) links or # headers in mrkdwn. Use the <url|label> link syntax and Block Kit header blocks for headings, since HTML tags are also stripped.

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