slack-mcp-server: Command for Claude Code

.claude/commands/slack-mcp-install.md

slack-mcp-install is a command for Claude Code from lazallen/slack-mcp-server. It costs 17 tokens per session (645 once invoked), scanned A, original, MIT.

A command that builds, installs, and checks a Slack MCP server. Slack is a team messaging service, and an MCP server is a local connector that lets an AI assistant use an outside system.

In plain words
What is it for?
Use it to install the Slack server, confirm that it runs, check its macOS Keychain setup, and report whether the required tokens are present.
Why use it?
It brings the installation, executable checks, wrapper verification, and secure Slack token checks into one ordered procedure.

Command for Claude Code

Written for Claude Code: installed under .claude/. Also seen: reads .claude/ paths; mentions CLAUDE.md; mentions Claude Code.

This is lazallen/slack-mcp-server's own configuration. It tells Claude Code how to work on slack-mcp-server itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything slack-mcp-server configures →

Not installable: its command points at a path on the author’s own machine, so it runs nowhere else. The line is /Users/lazallen/Projects/cerebro/slack-mcp-server/.

Reuse

Borrowing it

Nothing to install: this file belongs to lazallen/slack-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/lazallen/slack-mcp-server/master/.claude/commands/slack-mcp-install.md
Clone the repo
git clone --depth 1 https://github.com/lazallen/slack-mcp-server

Made for: Claude Code.

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README.md
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Your own site · 80×15
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Per session 17 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 645 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00017 $0.00645
Opus 5 $0.00009 $0.00322
Sonnet 5 $0.00003 $0.00129
Haiku 4.5 $0.00002 $0.00064

Measured 9d ago against content hash 1bdfb88c4301, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

slack-mcp-install scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/commands/slack-mcp-install.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Run a full install and config check for the Slack MCP server. Work through these steps in order:

1. Build & Install

Run make install from /Users/lazallen/Projects/cerebro/slack-mcp-server/. Report the output. If it fails, show the error and stop.

2. Verify Binary

Check the installed binary:

  • Exists at ~/bin/slack-mcp-server
  • Is executable (ls -la ~/bin/slack-mcp-server)
  • Runs without error (~/bin/slack-mcp-server --transport stdio killed immediately after launch, or just check it responds to help flags)

3. Check Wrapper Script

Verify /Users/lazallen/bin/slack-mcp-wrapper.sh:

  • Exists and is executable
  • Reads Slack MCP xoxc and Slack MCP xoxd from macOS Keychain
  • Ends with exec "$@"

4. Check Keychain Tokens

Run these commands and report whether each returns a non-empty value (do NOT print the token values):

security find-generic-password -a "$USER" -s "Slack MCP xoxc" -w 2>/dev/null | wc -c
security find-generic-password -a "$USER" -s "Slack MCP xoxd" -w 2>/dev/null | wc -c
  • If either returns 0: warn the user tokens are missing and show the refresh command from CLAUDE.md
  • If both are set: report tokens present

5. Check ~/.claude.json Config

Read ~/.claude.json and verify the slack-mcp entry matches this structure:

{
  "type": "stdio",
  "command": "/Users/lazallen/bin/slack-mcp-wrapper.sh",
  "args": ["/Users/lazallen/bin/slack-mcp-server", "--transport", "stdio"],
  "env": {
    "SLACK_MCP_ADD_MESSAGE_TOOL": "true",
    "SLACK_MCP_SAVED_LIST_TOOL": "true",
    "SLACK_MCP_SAVED_COMPLETE_TOOL": "true"
  }
}

Report any differences. If the binary path in args[0] is different (e.g. still pointing to the project build dir), update it to /Users/lazallen/bin/slack-mcp-server using python3 to parse and rewrite the JSON safely.

6. Summary

Print a clear status table:

Check Status
Binary built & installed ✓/✗
Wrapper script ✓/✗
Keychain token xoxc ✓/✗
Keychain token xoxd ✓/✗
~/.claude.json config ✓/✗

Read the full file on GitHub · 67 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 67 lines · 17 tokens per session scan A 1bdfb88c4301

Subscribe to this mod's changes

slack-mcp-install is a command published in the GitHub repository lazallen/slack-mcp-server (2 stars, last pushed 4mo ago), licensed MIT. It adds 17 tokens to every session and 645 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.