Block Kit

Help the developer build a rich Block Kit layout. If $0 is provided, it specifies the target surface (message, modal, or home-tab).

This skill walks through surface selection, layout planning, JSON generation, and validation. Block types, elements, and fields come from the live docs (see Source of Truth below) — discover them and read each component's schema there, never from memory.

Common Block Kit mistakes (and why): A few errors recur often enough to flag up front. Most others are caught by blocks.validate in Step 5, so lean on validation rather than memorizing rules.

• "type": "text" is not a thing. Text is a composition object: { "type": "plain_text", "text": "..." } or { "type": "mrkdwn", "text": "..." }.
• markdown is a block type, not a text type. A markdown block holds standard markdown; text objects inside other blocks use mrkdwn (see mrkdwn vs. the markdown block in Step 4). Slack's mrkdwn is *bold* / _italic_ / ~strike~, not **bold**.
• Messages need a top-level text fallback. blocks.validate won't flag a missing one, but notifications and screen readers display it instead of the blocks — so summarize what the layout conveys rather than leaving it empty.

Source of Truth: the Live Docs

Every block, element, and composition object is documented on docs.slack.dev. Append .md to any reference URL to fetch it as markdown with WebFetch (no auth required).