slackapi/slack-mcp-plugin/slack-cli

Slack CLI

Use the Slack CLI to create, run, and manage Slack apps — including calling Web API methods directly and searching Slack developer documentation from the terminal.

For initial setup (sandbox creation, project scaffolding from templates), use the create-slack-app skill instead.

Step 1: Detect the Slack CLI

Resolve the path to the public Slack CLI before running any other command. We refer to the resolved value as SLACK_CMD — substitute it everywhere below. Try 1a → 1b → 1c in order; do not skip ahead.

1a. Standard install path (preferred — no verification needed)

The official install scripts place the binary at a fixed per-user path. If the file exists, use it directly: only the install script writes to that path.

• macOS / Linux: ~/.slack/bin/slack
• Windows: %USERPROFILE%\AppData\Local\slack-cli\bin\slack.exe (or %USERPROFILE%\.slack-cli\bin\slack.exe as a fallback)

POSIX shell:

[ -x "$HOME/.slack/bin/slack" ] && echo "$HOME/.slack/bin/slack"

PowerShell:

$p = "$env:USERPROFILE\AppData\Local\slack-cli\bin\slack.exe"
if (Test-Path $p) { $p } elseif (Test-Path "$env:USERPROFILE\.slack-cli\bin\slack.exe") { "$env:USERPROFILE\.slack-cli\bin\slack.exe" }

If a path is returned, set SLACK_CMD to that absolute path and proceed to Step 2. Do not also run _fingerprint.

1b. slack on PATH (verify with fingerprint)

If 1a found nothing, try slack on PATH:

slack _fingerprint 2>/dev/null

If it outputs d41d8cd98f00b204e9800998ecf8427e, set SLACK_CMD=slack and proceed.

1c. Ask about an alias, or install

If 1b fails or returns a different value, ask the developer using AskUserQuestion:

• "The slack command on your system doesn't appear to be the public Slack CLI. Do you have it installed under a different name or alias?"
• Options: "Yes, it's aliased as..." (let them provide the alias), "No, I need to install it"
• If they provide an alias, verify it with <alias> _fingerprint 2>/dev/null and set SLACK_CMD=<alias>.
• If they need to install it, run:

``text curl -fsSL https://downloads.slack-edge.com/slack-cli/install.sh | bash ``

Then re-run 1a — the install script will have written ~/.slack/bin/slack.

Common mistakes: Don't use which slack to discover the binary — which resolves any shell alias and defeats the point of 1a. In Git Bash on Windows, use the POSIX probe form, not PowerShell.

Step 2: Command Discovery via Help

Always run `SLACK_CMD <command> --help` before constructing a command you have not used in the current session. Do not guess at flags — the help output is the source of truth.

• SLACK_CMD help — lists all available command groups
• SLACK_CMD <command> --help — shows subcommands, flags, and usage examples

Resolving --app and --team values

When a command requires --app or --team:

• App ID: Run SLACK_CMD app list from the project directory to see installed apps and their IDs.
• Team ID: Run SLACK_CMD auth list to see authenticated workspaces and their team IDs.

Step 3: Searching Documentation (slack docs search)

Search Slack's developer documentation directly from the terminal.

SLACK_CMD docs search "<query>" --output=text --limit=5

Use --output=text for concise terminal-readable results. Use this when you are already running CLI commands and want to:

• Check a Slack feature before implementing it
• Verify API behavior or required scopes
• Look up Block Kit elements, event types, or method parameters

Step 4: Calling Web API Methods (slack api)

Call any Slack Web API method directly. Run SLACK_CMD api --help for full details and examples.

Parameters are passed as positional key=value pairs (NOT --key=value flags):

SLACK_CMD api chat.postMessage channel=C0123456789 text="Hello from the CLI"

Important distinction: --team, --token, --json, and --data are meta-flags (prefixed with --). API method parameters use positional key=value syntax without dashes.

Reference: Full method list at <https://docs.slack.dev/reference/methods.md>.

Step 5: Authentication (slack auth)

When to run this flow

Slack auth is per-team, not a single boolean. Run the seamless login flow below whenever any of these is true:

• The developer is not authenticated to any team yet.
• The developer wants to add a new team / workspace / sandbox, even if SLACK_CMD auth list already shows other teams.
• The developer asks to log in, switch teams, or re-authenticate.

SLACK_CMD auth list showing other teams is not a reason to skip login — those are different teams. Ask the developer which team they want, then run the flow.

The flow below is the same for every kind of workspace. /slackauthticket works in any workspace the developer belongs to, whether that is a developer sandbox, a Free Team, or a production workspace, so there is no sandbox-specific login. Which target to prefer is the create-slack-app skill's call (Step 3: Choose Where to Install the App).

Inspect existing auth (optional)

SLACK_CMD auth list

Use this to show the developer which teams are already authenticated, or to confirm a successful login. Do not treat a non-empty list as "auth complete" when the developer asked to log in to a new team.

Run the seamless login flow

The agent drives this end-to-end — no separate terminal window, no browser confirmation.

SLACK_CMD login --no-prompt makes the CLI emit a single-use ticket and exit immediately instead of waiting on stdin. Slack itself renders the challenge code inside a workspace modal when the developer sends the /slackauthticket slash command — there is no browser step. The agent submits the challenge back to the CLI to complete login.

1. Start login and capture the ticket

SLACK_CMD login --no-prompt

The CLI prints a /slackauthticket <ticket> slash command and exits. Capture the ticket — you will need it in step 4. Sample output:

📋 Run the following slash command from any Slack channel in the workspace
   you'd like to authenticate
 
   /slackauthticket eyJ0eXAiOiJKV1QiLCJh…
 
? Slack will then show you a challenge code. Submit it via:
   slack login --ticket <ticket> --challenge <code>

2. Hand the slash command to the developer

Show the full /slackauthticket … line and ask the developer to paste it into the message box of the Slack workspace they want to authenticate, then send it. Slack responds with a modal containing a short challenge code (e.g. JDt1IK7X).

3. Collect the challenge code

Use AskUserQuestion to ask the developer for the challenge code shown in the Slack modal. Wait for their answer — do not guess or default.

4. Complete login

SLACK_CMD login --ticket <ticket> --challenge <code>

On success the CLI returns the team name and ID. Verify with SLACK_CMD auth list and report the team back to the developer.

Troubleshooting: tickets are single-use and time-limited. If step 4 fails with an invalid/expired ticket or wrong challenge, restart from step 1 with a fresh SLACK_CMD login --no-prompt — do not retry the same ticket.

Use --team <team_id> on individual commands to target a specific workspace without switching globally.

Red flags — STOP

If you catch yourself thinking any of these, you are about to regress to the old broken flow:

All of these mean: run `SLACK_CMD login --no-prompt` yourself and follow the four numbered steps above.

Step 6: Running an App Locally (slack run)

Run SLACK_CMD run --help for all available flags.

Resolve the app or team target

Run SLACK_CMD app list from the project directory to check for installed apps:

• If an app exists: Use --app=<app_id> in the run command.
• If no apps are listed: Use --team=<team_id> instead (get the team ID from SLACK_CMD auth list).

Start the dev server in the background

Run this command as a background process so the developer can continue working:

If an app ID was found:

cd <project-dir> && SLACK_CMD run --org-workspace-grant=all --app=<app_id>

If no apps — use the team ID:

cd <project-dir> && SLACK_CMD run --org-workspace-grant=all --team=<team_id>

Tell the developer the app is running in the background. They can ask:

• "What's the status of the dev server?" — to check on it
• "Show me the output from slack run" — to see activity logs
• "Stop the dev server" — to terminate the process

Step 7: Managing the Manifest

Run SLACK_CMD manifest --help for subcommands (validate, info) and the --source local|remote flag.

Use SLACK_CMD manifest validate before deploying or when something seems wrong with the app configuration.

Step 8: Other Commands

For any other command group (e.g., trigger, datastore, env, collaborator, external-auth, deploy), run SLACK_CMD <command> --help to discover subcommands and flags. Run SLACK_CMD help to see all available command groups.

Notes

• SLACK_CMD is a placeholder — always substitute the actual command name resolved in Step 1.
• Always run `--help` before constructing a command you have not used in the current session.
• Interactive commands (e.g., slack trigger create without --trigger-def) cannot be run in the background. Tell the developer to run these in a new terminal window. slack login is not in this category — drive it inline using the --no-prompt / --ticket / --challenge flow in Step 5.
• slack run runs locally for development. slack deploy deploys to Slack's hosted infrastructure, unless .slack/hooks.json defines a deploy hook, in which case it runs that hook instead (see the deploy-slack-app skill). These are different operations, so do not confuse them.