Agent skill

Slack App Setup

by vellum-ai in vellum-ai/vellum-assistant

Connect a Slack app to the Vellum Assistant via Socket Mode.

MITAuto-check: warnings

Install Slack App Setup

The automated check flagged lines worth reading first. See the safety section below.

skills CLI
$ npx skills add vellum-ai/vellum-assistant --skill slack-app-setup -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install vellum-ai/vellum-assistant slack-app-setup --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/vellum-ai/vellum-assistant.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/slack-app-setup .claude/skills/slack-app-setup && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
slack-app-setup
GitHub stars
1.4k
Token cost
~2.5k tokens
SKILL.md length
1,400 words
Files
2 (incl. scripts)
Skills in repo
108
Repo updated
First seen
Licence
MIT

At a glance

Connect a Slack app to the Vellum Assistant via Socket Mode.

  • Works in 5 steps: Check existing configuration → Open the setup wizard → Verify completion → …
  • The user wants to set up Slack for their assistant
  • SKILL.md covers Scope, Step 1 — Check existing…, Step 2 — Open the setup wizard and Step 3 — Verify completion, plus 6 more sections
  • Runs TypeScript scripts from its folder; calls bash; reaches slack.com

What it does

Slack App Setup is an agent skill from vellum-ai/vellum-assistant. Connect a Slack app to the Vellum Assistant via Socket Mode. Use whenever the user wants to set up Slack for their assistant, connect a workspace, or get the assistant talking in Slack — opens a guided setup wizard in the side panel so the user can create the app, generate tokens, and connect in one flow.

Its SKILL.md is about 2.5k tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including scripts (for example `scripts/build-manifest.ts`). Compatibility notes: Designed for Vellum personal assistants

It works with Slack. The repository describes itself as: An AI Assistant that’s easy to setup, does your work 24/7, knows your preferences and gets better over time. The licence is MIT.

When your agent uses it

  • The user wants to set up Slack for their assistant
  • Connect a workspace
  • Get the assistant talking in Slack — opens a guided setup wizard in the side panel so the user can create the app
  • Generate tokens

Example prompts

  • “/slack-app-setup”

Requirements

  • Node.js
  • Compatibility (from SKILL.md): Designed for Vellum personal assistants

Workflow steps

5 steps, taken from the step headings in SKILL.md.

  1. Check existing configuration
  2. Open the setup wizard
  3. Verify completion
  4. Verify identity (optional)
  5. Report success

What it can do on your machine

Read from SKILL.md and the folder at commit 844117a. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Ships 1 file in scripts/ (TypeScript), which the agent can run.

    Shell commands in SKILL.md call:

    • bash

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Hosts in commands or code, which the agent is likely to contact:

    • slack.com

    Also links to:

    • api.slack.com

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

  • Compatibility

    Designed for Vellum personal assistants

    From compatibility in the SKILL.md frontmatter.

Context cost

Slack App Setup loads about 2.5k tokens when it runs. Until then it costs about 81 tokens; SKILL.md has 1,400 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~81
When it runs · the whole SKILL.md, loaded when a task matches
~2.5k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check: warnings

The automated check found patterns that need a careful read before installing.

  • WarningTells the agent its actions are pre-authorized / not to stop for confirmationSKILL.md:61
    izard drawer sends it automatically, so do not wait for the user to type a confirmation. If the user manually says they'

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from vellum-ai/vellum-assistant at commit 844117a, republished under its MIT licence (© vellum-ai). 1,400 words, ~2,514 tokens.

Download SKILL.mdSave it as .claude/skills/slack-app-setup/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
slack-app-setup
description
Connect a Slack app to the Vellum Assistant via Socket Mode. Use whenever the user wants to set up Slack for their assistant, connect a workspace, or get the assistant talking in Slack — opens a guided setup wizard in the side panel so the user can create the app, generate tokens, and connect in one flow.
compatibility
Designed for Vellum personal assistants
metadata.emoji
💬

Scope

This skill connects an assistant to a Slack workspace: first-time bot identity (tokens, scopes, events), or switching workspaces and rotating tokens. Runtime Slack operations (posting, reading channels, triage) belong to the separate slack skill.

Step 1 — Check existing configuration

Run assistant credentials list --search slack_channel (via the bash tool). Scan the result for entries with service: slack_channel and note which of app_token, bot_token are present.

Then branch:

  • If both ✅ → fully configured. Offer to show status or reconfigure. Stop here unless the user wants a reset.
  • Otherwise → continue to Step 2.

✓ Checkpoint: You named which of app_token / bot_token are present before branching. Do not skip the assistant credentials list call and guess.

Step 2 — Open the setup wizard

Call ui_show with surface_type: "channel_setup" and data: { channel: "slack" }. This opens the Slack setup wizard in the side panel. The wizard is non-blocking — the tool returns immediately.

⚠️ CRITICAL: Tool call first, announcement second — in the same turn. Do not write any message that says the wizard is open (or is opening) until the ui_show call has returned success earlier in the same turn. A message claiming the wizard is open when the tool was never called shows the user an empty side panel.

After ui_show returns success, tell the user:

I've opened the Slack setup wizard in the side panel. It will walk you through creating a Slack app from a manifest and connecting it — complete the steps there. The wizard will auto-notify me when you close it. If you run into issues along the way, ask me in chat.

Hand-off notification (phones and narrow windows). On phone-sized clients the setup opens on the Contacts page instead of a side drawer, and completing it there cannot auto-notify. The client signals this with a hidden message like [User action on channel_setup surface: moved the slack setup to the Contacts page]. When you receive that hand-off notification, tell the user:

It looks like the setup opened on your Contacts page rather than a side panel — same steps, different spot. When you've finished, come back here and tell me, and I'll verify the connection.

and rely on their confirmation to trigger Step 3 (no wizard-closed notification will arrive).

If the ui_show call fails, do NOT send that message — tell the user the wizard could not be opened and troubleshoot (e.g. no connected client) before retrying.

✓ Checkpoint: The successful ui_show tool result appears earlier in this turn than your announcement. If it does not, the wizard is not open — make the call before claiming it is.

The wizard handles the entire flow: manifest generation, app creation in Slack, and credential storage. The user copies the manifest from the wizard, hands it to Slack's From a manifest option, and Slack returns both tokens at once on Create and Install. Tokens are entered in secure input fields within the wizard and saved directly via the API — they never enter the chat conversation.

⚠️ CRITICAL: Do NOT collect tokens in chat. Do NOT use assistant credentials prompt for Slack setup. Do NOT ask the user to paste tokens into the conversation. The wizard's secure input fields are the only path for credential entry.

Step 3 — Verify completion

When you receive the wizard-closed notification (or the user says they're done, or asks you to check), verify the connection. The notification arrives as a message like [User action on channel_setup surface: closed the slack setup wizard] — closing the wizard drawer sends it automatically, so do not wait for the user to type a confirmation. If the user manually says they're done or asks you to check, proceed with the same verification.

  1. Run assistant credentials list --search slack_channel (via the bash tool). Confirm both app_token and bot_token are present.

  2. If both are present, fetch the bot identity:

    bash {
      command: "curl -s -X POST https://slack.com/api/auth.test"
      network_mode: "proxied"
      credential_ids: ["slack_channel/bot_token"]
      activity: "to verify bot identity"
    }

    Extract user → botUsername, team → workspace from the JSON response. If ok: false or the call errors, fall back to your bot / your workspace.

  3. If either token is missing, tell the user which one is missing. When verification was triggered by the wizard-closed notification, the side panel is no longer open — offer to re-open it and re-run Step 2's ui_show call if they accept. When the user asked manually, the wizard may still be open in the side panel — point them back to it instead of re-opening (a second ui_show over a live wizard resets their progress).

Step 4 — Verify identity (optional)

Load the guardian-verify-setup skill:

  • skill_load with skill: "guardian-verify-setup".

If the user wants to skip → continue to Step 5, and let them know they can run it later by saying "verify me on slack".

Step 5 — Report success

⚠️ CRITICAL: Never post the success message with literal {botUsername} or {workspace} in it. Those are placeholders. Run auth.test first (Step 3), substitute real values, then post.

If identity was verified:

Setup complete! ✅ App created ✅ Tokens configured ✅ Connection active ✅ Connection tested

Connected: @<botUsername> in <workspace> Channels: @mention the bot in any channel to add it, or use /invite @<botUsername>. DMs work immediately. Identity: verified

Want full workspace visibility (read every channel you're in, even ones the bot isn't a member of)? Ask me to add a User OAuth Token later.

If identity was skipped → swap the last two lines for:

⬜ Connection tested — say "verify me on slack" to finish later. … Identity: skipped

Show full SKILL.md (524 more words)Show less

SKILL COMPLETE WHEN

  • assistant credentials list was called and the existing-state branch was named explicitly (Step 1).
  • ui_show with surface_type: "channel_setup" was called and returned success before any message claiming the wizard is open (Step 2).
  • The wizard-closed notification arrived (or the user asked to check) and both tokens are verified present (Step 3).
  • guardian-verify-setup was loaded and either completed or the user explicitly declined (Step 4).
  • Success message was posted with real bot identity values (Step 5).

If Something Fails

Bot doesn't respond in a channel. The bot must be a member. @mention it (Slack will prompt "Add Them") or /invite @{botUsername}.

Socket Mode keeps disconnecting. The app token is revoked or expired. Regenerate it in Basic Information → App-Level Tokens and re-enter it in the wizard.

Token rejected on save. The wizard validates token prefixes on entry. Double-check you copied the right value — bot token starts xoxb-, app token xapp-.

Messages not arriving. Verify Event Subscriptions → Subscribe to bot events includes message.channels. The manifest pre-configures it, but it can be edited out by hand.

No tokens after creating the app. Slack shows both under Your app credentials in the "your app is ready" modal, collapsed behind a toggle — expand it. If that panel is missing entirely, the app was created from a template (AI agent, Starter app, Blank app) rather than From a manifest; scopes will be wrong too, so start over from Step 1. Do not hand-edit scopes.

Calls fail with missing_scope even though setup succeeded. Slack sometimes installs an app carrying only a fraction of the manifest's scopes. auth.test still passes, so a green connection check does not prove the scopes arrived. Confirm by reading the x-oauth-scopes response header on any Slack API call and comparing it against the scopes in the manifest.

To fix, in this order:

  1. Open the app at https://api.slack.com/apps. Slack interrupts with a prompt to update the app — accept it. Reinstalling without this step does not restore the scopes.
  2. Go to OAuth & Permissions → Reinstall to Workspace.

The same bot token then carries the full scope set — it is not rotated, so nothing needs re-entering in the wizard.

Optional: add a User OAuth Token later

A User OAuth Token (xoxp-...) lets the assistant see every channel you're in, even ones the bot was never invited to. Useful for triage workflows where you want the assistant to summarize across the whole workspace. Not needed for normal messaging — the bot token alone covers every channel the bot is a member of.

To add it later:

  1. Open your Slack app at https://api.slack.com/apps, pick the app this skill created, go to Install App.
  2. Copy the User OAuth Token (xoxp-...).
  3. Ask the assistant to store the User OAuth Token — it will send you a secure prompt to paste it into. (Under the hood: assistant credentials prompt --service slack_channel --field user_token.)

To revoke it later, clear the user_token credential the same way you'd clear any Slack credential — see Clearing Credentials below.

Clearing Credentials

To disconnect, prefer the Settings UI path so the same Slack settings handler used by Settings clears both the secure tokens and the workspace metadata together.

© vellum-ai, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (scripts) in skills/slack-app-setup of vellum-ai/vellum-assistant.

  • SKILL.md
  • scripts/build-manifest.ts

Open the folder on GitHubat commit 844117a

Compare with similar skills

Slack App Setup next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

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Slack App Setup this skillvellum-ai/vellum-assistant1.4k—~2.5kAutomated safety check: WarnMIT
Agent Browser CLIvercel-labs/agent-browser44k24 repos~864Automated safety check: PassApache-2.0
Slack GIF Creatoranthropics/skills180k29 repos~2kAutomated safety check: PassApache-2.0
Code Design Rationale Investigatorcursor/plugins10k9 repos~2.6kAutomated safety check: PassNone
Electron App Automationvercel-labs/agent-browser44k5 repos~1.7kAutomated safety check: PassApache-2.0
Slack Browser Automationvercel-labs/agent-browser44k1 repos~2.1kAutomated safety check: PassApache-2.0

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Works with

Questions about Slack App Setup

What does Slack App Setup do?

Connect a Slack app to the Vellum Assistant via Socket Mode. Slack App Setup is an agent skill from vellum-ai/vellum-assistant. Connect a Slack app to the Vellum Assistant via Socket Mode.

When should I use Slack App Setup?

Slack App Setup fits situations like: the user wants to set up Slack for their assistant; connect a workspace; get the assistant talking in Slack — opens a guided setup wizard in the side panel so the user can create the app; generate tokens.

How do I install Slack App Setup in Claude Code?

Run `npx skills add vellum-ai/vellum-assistant --skill slack-app-setup -a claude-code`. Or copy the skill folder (skills/slack-app-setup in vellum-ai/vellum-assistant) into .claude/skills/slack-app-setup in your project. Claude Code loads it when a task matches its description.

How do I install Slack App Setup in Codex?

Run `npx skills add vellum-ai/vellum-assistant --skill slack-app-setup -a codex`. Or copy the skill folder (skills/slack-app-setup in vellum-ai/vellum-assistant) into .agents/skills/slack-app-setup in your project. Codex loads it when a task matches its description.

Can I use Slack App Setup in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add vellum-ai/vellum-assistant --skill slack-app-setup -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/slack-app-setup, .gemini/skills/slack-app-setup, .github/skills/slack-app-setup and .opencode/skills/slack-app-setup in your project.

What does Slack App Setup need to run?

Going by SKILL.md and its folder, Slack App Setup needs TypeScript for the scripts in its folder and the command-line tools its instructions call (bash). Our summary lists: Node.js. Compatibility (from SKILL.md): Designed for Vellum personal assistants.

Does Slack App Setup access the network?

SKILL.md names 2 domains. In commands or code: slack.com; the agent is likely to contact it when it follows the instructions. As links in the text: api.slack.com. This is read from the text; nothing was executed.

Is Slack App Setup safe to install?

Our automated static check of SKILL.md flagged 1 warning(s): tells the agent its actions are pre-authorized / not to stop for confirmation. Read the flagged lines before installing; the check is not a guarantee either way. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.

What licence does Slack App Setup use?

Slack App Setup is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Slack App Setup use?

About 2.5k tokens (SKILL.md is roughly 10k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Slack App Setup?

Skills that share tags, products or a category with Slack App Setup: Agent Browser CLI (vercel-labs/agent-browser, 44k stars), Slack GIF Creator (anthropics/skills, 180k stars), Code Design Rationale Investigator (cursor/plugins, 10k stars) and Electron App Automation (vercel-labs/agent-browser, 44k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Slack App Setup?

vellum-ai (a GitHub organization) maintains it in vellum-ai/vellum-assistant, which has 1,400 GitHub stars. The repository holds 108 skills in this directory. The repository was last updated on October 9, 2026.

Source: vellum-ai/vellum-assistant on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.