slack

slack is a skill for Claude Code, Codex from tallclub/matimo. It costs 25 tokens per session (1,938 once invoked), scanned A, original, MIT.

A set of tools for working with Slack, a team chat platform, from a coding agent.

In plain words
What is it for?
Use it to send channel messages and direct messages, reply in threads, search messages, manage channels, look up users, add reactions, and upload files.
Why use it?
It removes the need to switch between the agent and Slack to read conversations, find messages, contact people, or share files.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/tallclub/matimo/slack
Any agent
npx skills add tallclub/matimo --skill slack
Clone the repo
git clone --depth 1 https://github.com/tallclub/matimo

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for slack

README.md
[![agentmods](https://agentmods.dev/badge/skills/tallclub/matimo/slack.svg)](https://agentmods.dev/skills/tallclub/matimo/slack)
Your own site
<a href="https://agentmods.dev/skills/tallclub/matimo/slack"><img src="https://agentmods.dev/badge/skills/tallclub/matimo/slack.svg" alt="Measured on agentmods" height="20"></a>
Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,938 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00025 $0.01938
Opus 5 $0.00013 $0.00969
Sonnet 5 $0.00005 $0.00388
Haiku 4.5 $0.00003 $0.00194

Measured 6d ago against content hash 7a64aa76b528, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

slack 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 6d 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.

typescript/packages/slack/skills/slack/SKILL.md · 221 lines

How it starts

The opening of the file, as written. The whole thing — 221 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Slack

Complete guide to using Matimo's Slack tools for messaging, channels, users, search, and file sharing.

All Available Tools

Tool Purpose Category
slack_send_channel_message Post a message to a channel Messaging
slack_reply_to_message Reply in a thread Messaging
slack_add_reaction Add an emoji reaction Messaging
slack_get_reactions Get reactions on a message Messaging
slack_get_channel_history Read recent messages from a channel Messaging
slack_get_thread_replies Get all replies in a thread Messaging
slack_send_dm Send a direct message to a user Users
slack_search_messages Search across all channels Search
slack_get_user_info Look up a user's profile Users
slack-get-user Get basic user details Users
slack_upload_file Upload a file to a channel or DM Files
slack-list-channels List available channels Channels
slack-send-message Send a message (simplified) Messaging
slack_create_channel Create a new channel Channels
slack_set_channel_topic Set or update the channel topic Channels
slack_join_channel Join an existing channel Channels

Authentication

All Slack tools require a SLACK_BOT_TOKEN environment variable. The bot must have the relevant OAuth scopes (chat:write, channels:read, channels:history, users:read, search:read, files:write).


Channel Messaging

Sending a Message

Use slack_send_channel_message to post to any public or private channel the bot is a member of.

Parameter Type Required Description
channel string Yes Channel ID (C01ABCDEF) or name (#general)
text string No Plain-text message body
blocks array No Block Kit UI layout for rich formatting

Best practices:

  • Always provide text even with blocks — it's the notification preview and screen reader fallback
  • Use channel IDs over names for reliability (names can change)
  • Keep messages under 4000 characters; split longer content

Read the full file on GitHub · 221 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. 6d ago First seen · 221 lines · 25 tokens per session scan A 7a64aa76b528

Subscribe to this mod's changes

slack is a skill published in the GitHub repository tallclub/matimo (11 stars, last pushed 2d ago), licensed MIT. It adds 25 tokens to every session and 1,938 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 2026-08-30.