co-slack

co-slack is a skill for Claude Code, Codex from openonion/connectonion. It costs 41 tokens per session (811 once invoked), scanned A, original, Apache-2.0.

A command-line tool for reading and replying to Slack, a team messaging service. It can inspect channels, message history, threads, and search results, then reply in an existing thread.

In plain words
What is it for?
Use it to find what a channel or thread said, search for messages, inspect available channels, and send a reply to a specific message thread.
Why use it?
It brings team conversations into coding-agent workflows and helps preserve the context of a thread. The listed inbox features are experimental and do not yet run on a live workspace.

Skill for Claude CodeCodex

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

Good fit Use it to find what a channel or thread said, search for messages, inspect available channels, and send a reply to a specific message thread.

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Install with agentmods
npx agentmods add skills/openonion/connectonion/co-slack
About the project

ConnectOnion is an open-source, template-first toolkit for building, debugging, deploying, and operating AI agents. Developers use its command-line tools and Python runtime to create agents, add tools, connect services, deploy them, and make them callable by other agents, while the catalogue entries are related agents, skills, and instructions.

openonion/connectonion · 1,497 stars · on GitHub · docs.connectonion.com

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.

Any agent
npx skills add openonion/connectonion --skill co-slack
Clone the repo
git clone --depth 1 https://github.com/openonion/connectonion

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 co-slack

README.md
[![agentmods](https://agentmods.dev/badge/skills/openonion/connectonion/co-slack/github.svg)](https://agentmods.dev/skills/openonion/connectonion/co-slack)
Your own site
<a href="https://agentmods.dev/skills/openonion/connectonion/co-slack"><img src="https://agentmods.dev/badge/skills/openonion/connectonion/co-slack/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for co-slack

Your own site · 80×15
<a href="https://agentmods.dev/skills/openonion/connectonion/co-slack"><img src="https://agentmods.dev/badge/skills/openonion/connectonion/co-slack.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 811 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 $0.00041 $0.00811
Opus 5.5 $0.00016 $0.00324
Sonnet 5.5 $0.00008 $0.00162
Haiku 4.5 $0.00004 $0.00081

Measured 15d ago against content hash 6983e87c33e1, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

co-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 15d 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.

connectonion/useful_skills/co-slack/SKILL.md · 64 lines

How it starts

The opening of the file, as written. The whole thing — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Slack

co slack is the user's own Slack app. Read verbs ask Slack directly (Web API); inbox verbs (listen, receive, reply) only see what arrived while a listener ran. It is experimental: not yet run on a live workspace.

Read the help before the first command, and read every output, not just the exit code:

co slack --help                 # every verb; the "Read the workspace" panel is channels, history, thread, search
co slack <verb> --help          # flags and an example for that verb

Which command

the user wants run
set it up, or fix a token co auth slack
know whether it works co slack check
which channels exist (ids, names) co slack channels
what a channel said co slack history ops -n 50
a whole conversation under a message co slack thread <channel>:<ts>
find a message by its words co slack search "words" --in ops --from alice
answer in a message's thread co slack send <channel> "text" --reply-to <channel>:<ts>

Add --json to any read verb for one object per line: id, chat, thread, at (UTC), sender, sender_name, text, and replies (history and thread).

"What did #ops say today?"

  1. co slack history ops -n 100 --json (a name, or '#ops' quoted: an unquoted # is a shell comment).
  2. Keep the messages whose at falls on today in the user's timezone; the plain view already prints local time.
  3. For any message with replies > 0 that matters, co slack thread <id>.
  4. Answer from what was said, citing who said it. Do not post anything.

"Find the message about X and reply in its thread"

  1. co slack search "X" -n 10 (narrow with --in / --from). Without SLACK_USER_TOKEN it exits 1 and says so: fall back to co slack history <channel> on the likely channel, or tell the user to run co auth slack and paste the User OAuth Token.
  2. Read the thread before answering: co slack thread <id>.
  3. Show the user the reply and get their yes. Then co slack send <channel> "reply" --reply-to <id>, using that message's chat and id. It prints the new message's id.

Read the full file on GitHub · 64 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. 15d ago First seen · 64 lines · 41 tokens per session scan A 6983e87c33e1

Subscribe to this mod's changes

co-slack is a skill published in the GitHub repository openonion/connectonion (1,497 stars, last pushed today), licensed Apache-2.0. It adds 41 tokens to every session and 811 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-10-02.