Slack

Reviewed 2026-10-21productivityPrompt / Rule# slack # mcp # block-kit # messaging # slack-api

Slack's official skills plugin: Slack MCP server plus skills for messaging, search, Web API, Slack CLI, Block Kit and building Slack apps.

Security Reviewed

Mostly Markdown instructions plus the hosted Slack MCP server (OAuth); only deploy-slack-app ships shell scripts, which send your Slack tokens to Railway or Heroku.

Install Slack in Google Antigravity

Antigravity loads skills from .agents/skills/ in your project or ~/.gemini/config/skills/ for all projects (official docs). Full guide

EasiestOption 1: paste this to your Antigravity agent

Install the "Slack" skill for Google Antigravity.
Follow the steps at https://www.antigravityskills.org/install/slack-skill.md (source: https://github.com/slackapi/slack-skills-plugin/tree/main/skills).
Before running anything, show me what you will download and whether it includes scripts, and wait for my OK.
Install it into this project (.agents/skills/) unless I say global. When done, check that Antigravity lists it as an installed skill.

The agent reads the install file, shows you what it will download and waits for your OK.

Option 2: install it yourself

1. Clone the source repository
```
git clone --depth 1 https://github.com/slackapi/slack-skills-plugin /tmp/slack-skills-plugin
```
Download Slack's official plugin repository into a temporary folder.
2. Copy the skills into your workspace
```
mkdir -p .agents/skills && cp -r /tmp/slack-skills-plugin/skills/* .agents/skills/
```
Run this from your project root. It copies the nine skill folders (slack-messaging, slack-search, slack-api, slack-cli, slack-docs, create-slack-app, test-slack-app, block-kit, deploy-slack-app) into .agents/skills/. Copy single folders if you only need some; skip deploy-slack-app unless you want the Railway/Heroku scripts.
3. Or install them globally
```
mkdir -p ~/.gemini/config/skills && cp -r /tmp/slack-skills-plugin/skills/* ~/.gemini/config/skills/
```
Use this instead of the workspace copy to make the skills available in every project.
4. Check that Antigravity sees them
Ask "What skills do you have?" (Antigravity 2.0 app has no /skills command). Antigravity CLI: run /skills; in a session that was already open, run /skills reload first. Look for slack-messaging, block-kit and the others.

The README does not mention Antigravity (it documents Claude Code, Cursor, Codex and `npx skills -a <agent>`). Copying the folders gives you the skills only. Sending or searching Slack messages needs Slack's MCP server (https://mcp.slack.com/mcp, OAuth, workspace admin approval), whose setup the repo documents for Claude Code and Cursor only. Developer skills use the Slack CLI or a Slack bot/user token.

Using Claude Code, Cursor or Codex? See other assistants below.

What is Slack?

slack-skills-plugin is Slack's official plugin for Claude Code, Cursor and Codex, published by slackapi. It connects your AI tool to Slack's hosted MCP server (https://mcp.slack.com/mcp) for search, messaging, canvases and user lookups, and ships a skills/ folder with nine SKILL.md skills: slack-messaging, slack-search, slack-api, slack-cli, slack-docs, create-slack-app, test-slack-app, block-kit and deploy-slack-app. It also adds five slash commands such as /slack:summarize-channel and /slack:standup in Claude Code.

How to use Slack?

In Claude Code or Cursor, install the plugin from the official marketplace and sign in to Slack with OAuth on first use. For other agents, install only the skills with `npx skills add`. Then ask in plain language, for example to search messages, draft an announcement or build a Block Kit modal.

Key features of Slack

✓We counted at 9aa77f1 (repo HEAD, plugin version 1.5.0, 2026-10-19): skills/ holds 9 SKILL.md skills (slack-messaging, slack-search, slack-api, slack-cli, slack-docs, create-slack-app, test-slack-app, block-kit, deploy-slack-app) in 20 files and 104,639 bytes of SKILL.md text, plus 5 slash commands in commands/ (channel-digest, draft-announcement, find-discussions, standup, summarize-channel).
✓We counted: block-kit has 8 files (SKILL.md plus 7 reference documents on modal, App Home, data display, agent progress and human-in-the-loop design); deploy-slack-app has 5 files (SKILL.md, two provider guides and the deploy-railway.sh and deploy-heroku.sh hook scripts). Those 2 shell scripts are the only executable files in skills/.
✓We counted: the skills and commands name 15 distinct slack_* MCP tools (for example slack_send_message, slack_send_message_draft, slack_schedule_message, slack_search_public, slack_read_thread, slack_create_canvas). The draft-announcement command saves a draft with slack_send_message_draft instead of posting.
✓README says the hosted MCP server is https://mcp.slack.com/mcp, you sign in with OAuth, and your workspace admin must approve MCP integration first. Codex and the `npx skills` path get the skills only: no commands and no MCP server.
✓deploy-slack-app only supports Socket Mode apps and says it is verified on macOS and Linux, not Windows; its Railway script passes the Slack tokens on stdin while the Heroku script has to pass them as heroku config:set arguments (a comment in the script says so).
✓New since our earlier review: the repo added public/agent-setup/prompt.md, Slack's official copy-paste prompt for setting up a coding agent. For agents other than Claude Code and Codex it tells the agent to run `npx -y skills add slackapi/slack-skills-plugin -g -y -a <agent>`. Antigravity is not named in the README or the prompt.

When to use Slack

1Search Slack for messages about a launch from the last week
2Summarize recent activity in a channel or draft an announcement
3Build and validate a Block Kit modal
4Scaffold a new Slack app or agent with Bolt for JS or Python
5Debug a Web API error like missing_scope or invalid_auth

Installation & Setup Guide

Agent Rules / Prompt Setup

Follow these steps (taken from the project's own docs) to configure Slack in your development environment.

Step 1: Claude Code pluginclaude

/plugin install slack@claude-plugins-official

Installs skills, commands and the Slack MCP server; you sign in with OAuth on first use (README).

Step 2: Cursor plugincursor

/add-plugin slack

From the official Cursor Marketplace; installs skills, commands and the MCP server (README).

Step 3: Other agents (skills only)gemini

npx skills add slackapi/slack-skills-plugin -y -a gemini-cli

Replace gemini-cli with your agent's identifier (README names opencode, crush, devin, hermes-agent, openclaw, pi); add -g for a user-wide install; no commands or MCP server.

Usage Example & Verification

Prompt / Request Example

1) README example: "Summarize the last day of activity in #engineering".
-> Uses the Slack MCP server to read the channel and summarize it (the repo also ships a /slack:summarize-channel command for Claude Code).

2) README example: "Build a Block Kit feedback modal with a rating select and a comments field".
-> Uses the block-kit skill: picks the surface, plans the layout, writes the JSON and validates it.

3) Our example: "Find the Slack Web API method for scheduling a message and tell me which token type and scopes it needs."
-> The slack-api skill tells the agent to read the method's docs page and report its scopes and whether a bot (xoxb-) or user (xoxp-) token is accepted.

Security Review

Static review

Reviewed Date

2026-10-21

Audited Ref / Commit

9aa77f187c355f0caad9fea19a5667fbbeae59f0

Reviewer

antigravityskills.org (static code review)

Mostly Markdown instructions plus the hosted Slack MCP server (OAuth); only deploy-slack-app ships shell scripts, which send your Slack tokens to Railway or Heroku.

Full review: scope, findings, risks

Audit Scope:slackapi/slack-skills-plugin at 9aa77f1 (HEAD, 2026-10-19, package version 1.5.0). Our earlier review was at 42ad160; since then only skills/block-kit/SKILL.md and skills/create-slack-app/SKILL.md changed (argument handling and a hand-off to block-kit) and public/agent-setup/prompt.md was added. We re-read both changed skills, the new prompt, the two deploy scripts, the draft-announcement command, .mcp.json, .cursor-mcp.json, .agents/plugins, SECURITY.md and the README install sections, and recounted every number. Static review only.

Key Findings:Eight skills are instructions only. deploy-slack-app adds two shell hook scripts (Railway, Heroku) that need the provider CLI logged in and SLACK_BOT_TOKEN and SLACK_APP_TOKEN set. The skills tell the agent to use the Slack MCP tools, Slack CLI commands and curl to slack.com/api with a token you supply; slack-cli suggests installing the Slack CLI with a curl-to-bash script from downloads.slack-edge.com. No token is stored in the repo.

Identified Operational Risks & Permissions:Through the MCP server the agent can read and post in your Slack workspace under your OAuth sign-in. deploy-slack-app sends your Slack tokens to Railway or Heroku and pushes your project there. Developer skills use bot/user tokens (xoxb-/xoxp-) that you must keep out of chat and committed code.

Each folder in skills/ has a SKILL.md (block-kit also has 7 references/ Markdown files; deploy-slack-app has references/ with two provider guides and two shell scripts). .mcp.json and .cursor-mcp.json point to the hosted server https://mcp.slack.com/mcp with OAuth client IDs, so no token is stored in the repo. skills/slack-api/SKILL.md tells the agent how to call https://slack.com/api/<method> with curl and an `Authorization: Bearer xoxb-...` header, using a token the developer copies from the app's OAuth & Permissions page. skills/slack-cli/SKILL.md suggests `curl -fsSL https://downloads.slack-edge.com/slack-cli/install.sh | bash` if the Slack CLI is missing. skills/block-kit/SKILL.md validates JSON with the public blocks.validate method via the Slack CLI or curl. skills/create-slack-app/SKILL.md runs `slack create`, `slack sandbox create` and `slack env set` and states not to store or echo API key values. skills/test-slack-app/SKILL.md limits testing to developer sandboxes or Free Teams. skills/deploy-slack-app uses the Slack CLI deploy hook: references/deploy-railway.sh sends SLACK_BOT_TOKEN and SLACK_APP_TOKEN to a Railway service on stdin and runs `railway up`; references/deploy-heroku.sh runs `heroku config:set` with the tokens as arguments and `git push heroku`. Both scripts check that the tokens are set and the railway or heroku CLI is logged in before acting, and the skill only covers Socket Mode apps. scripts/ (cursor.py, sync_versions.py, changeset_version.sh) are build helpers that agents do not load. This is a static review; we did not run any of it.

Operational Notes & Known Limitations

Known Limitations

•The MCP server needs Slack OAuth, and your workspace admin must approve the MCP integration (README limitation).
•The `npx skills` path and manual copies install the skills only: no commands and no MCP server (README).
•Developer skills rely on the Slack CLI (create-slack-app, slack-cli) or Slack tokens (xoxb-/xoxp-) for API calls.
•Messaging and search skills expect the Slack MCP tools (slack_send_message, slack_search_public ...) to be available.
•deploy-slack-app supports Socket Mode apps only, is verified on macOS and Linux (not Windows), and deploys your project to Railway or Heroku with your logged-in CLI.

Frequently Asked Questions

Is the Slack skill safe?

In our static review of commit 9aa77f1, eight of the nine skills are Markdown only; deploy-slack-app also ships two shell scripts that run the railway or heroku CLI to set your Slack tokens on a host and deploy your project, so read it before approving. Through the MCP server the agent can read and send messages in your workspace under your OAuth sign-in. The developer skills tell the agent to run Slack CLI commands (including a curl install script from downloads.slack-edge.com) and curl calls to slack.com/api.

How do I install the Slack skill in Antigravity?

The README does not mention Antigravity. Clone https://github.com/slackapi/slack-skills-plugin to /tmp and copy the folders in skills/ into .agents/skills/ (or ~/.gemini/config/skills/), then ask "What skills do you have?" (Antigravity CLI: /skills). You get the skills; the messaging and search skills need Slack MCP tools to act on Slack.

Is this the slack-gif-creator skill?

No. slack-gif-creator in anthropics/skills makes animated GIFs for Slack. This is Slack's own plugin for messaging, search, the Web API and app development.

Do I need admin approval?

Yes for the MCP server: the README says your Slack workspace admin must approve MCP integration before you can authenticate.

Can it build Slack apps?

Yes. create-slack-app scaffolds a Bolt (JS or Python) app with the Slack CLI, slack-cli covers running the Slack CLI, deploy-slack-app hosts a Socket Mode app on Railway or Heroku, and test-slack-app tests it in a developer sandbox or Free Team, never a workspace with real users.

Supported Platforms

antigravityclaudecursorgemini

View Source on GitHub

Keep exploring this topic

Browse the full Antigravity skills directory for more source-linked skills with install steps and static safety reviews.

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