What is slack-message?

A small tool for sending messages to Slack, a team chat service, through an incoming webhook.

It posts messages and can use a configured webhook, channel, username, and message text.

It provides a way for automated workflows to notify a Slack channel without manually copying and posting updates.

slack-message — Skill for Claude Code and Codex by Livus-AI

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 Livus-AI/Skills-MCP --skill slack-message

Clone the repo

git clone --depth 1 https://github.com/Livus-AI/Skills-MCP

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/livus-ai/skills-mcp/slack-message/github.svg)](https://agentmods.dev/skills/livus-ai/skills-mcp/slack-message)

Your own site

<a href="https://agentmods.dev/skills/livus-ai/skills-mcp/slack-message"><img src="https://agentmods.dev/badge/skills/livus-ai/skills-mcp/slack-message/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/livus-ai/skills-mcp/slack-message"><img src="https://agentmods.dev/badge/skills/livus-ai/skills-mcp/slack-message.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 475 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.

Model	Per session	Once invoked
Fable 5.1	$0.00030	$0.00475
Opus 5	$0.00015	$0.00237
Sonnet 5	$0.00006	$0.00095
Haiku 4.5	$0.00003	$0.00047

Measured 11d ago against content hash e29b9b60a866, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

slack-message 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 11d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/post.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/slack-message/SKILL.md · 80 lines

What it actually says

Slack Message Skill

Send messages to Slack channels using incoming webhooks.

Prerequisites

You need a Slack Incoming Webhook URL. To get one:

Go to your Slack workspace's App Directory
Search for "Incoming Webhooks" and add it
Choose a channel and copy the webhook URL
Either set SLACK_WEBHOOK_URL environment variable or pass it as a parameter

Available Scripts

post.py - Post a message to Slack

How to Use

Basic Usage

execute_skill_script("slack-message", "post.py", {
    "message": "Hello from Skills MCP!"
})

With Webhook URL

execute_skill_script("slack-message", "post.py", {
    "webhook_url": "https://hooks.slack.com/services/...",
    "message": "Deployment completed successfully! ✅"
})

Parameters

Parameter	Type	Required	Description
`message`	string	Yes	The message text to post
`webhook_url`	string	No	Slack webhook URL (or set SLACK_WEBHOOK_URL env var)
`channel`	string	No	Override the default channel
`username`	string	No	Override the bot username

Example Response

Success:

{
  "status": "success",
  "message": "Message posted to Slack successfully",
  "timestamp": "2024-12-30T12:00:00"
}

Error (no webhook):

{
  "status": "error",
  "message": "No webhook_url provided and SLACK_WEBHOOK_URL not set"
}

Security Notes

Never commit webhook URLs to version control
Use environment variables for sensitive credentials
Webhook URLs should be treated as secrets

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

scripts/post.py 2.6 KB runs code

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.

11d ago First seen · 80 lines · 30 tokens per session scan A e29b9b60a866

Subscribe to this mod's changes

slack-message is a skill published in the GitHub repository Livus-AI/Skills-MCP (2 stars, last pushed 3mo ago), licensed MIT. It adds 30 tokens to every session and 475 once invoked, about $0.0002 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.

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Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

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