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.
npx skills add tomeraitz/claude-slack-bridge --skill slack-webhookgit clone --depth 1 https://github.com/tomeraitz/claude-slack-bridgeWrote 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.
[](https://agentmods.dev/skills/tomeraitz/claude-slack-bridge/slack-webhook)<a href="https://agentmods.dev/skills/tomeraitz/claude-slack-bridge/slack-webhook"><img src="https://agentmods.dev/badge/skills/tomeraitz/claude-slack-bridge/slack-webhook.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00059 | $0.00800 |
| Opus 5 | $0.00030 | $0.00400 |
| Sonnet 5 | $0.00012 | $0.00160 |
| Haiku 4.5 | $0.00006 | $0.00080 |
Grade A, and why
slack-webhook 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 8d 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.
How it starts
The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Send Slack messages as Claude
One command, one message, straight into the user's Slack.
python skills/slack-webhook/send.py "Migration finished — 412 rows moved, no errors."
Use this, not the Slack connector
The built-in Slack tools authenticate as the user, so anything they post looks like the user talking to themselves — and Slack doesn't notify anyone about their own message. This script posts through a webhook owned by the Claude app, so it arrives as Claude and can @-mention the user for a real notification.
Never reach the user through the Slack connector. If this script fails, say so rather than quietly falling back to it.
Options
# ping the user so their phone lights up
send.py --mention U0123ABCDEF "Need a decision before I continue."
# a different channel (each webhook is bound to one)
send.py --to design "New mockups are in the PR."
# short one-liners, Slack's own syntax, raw emoji
send.py --plain ":white_check_mark: build green"
# what's available
send.py --list
| Flag | Does |
|---|---|
--mention U… |
@-mentions that member — the thing that actually pushes a notification |
--to NAME |
picks a configured webhook; each one posts to a fixed channel |
--plain |
sends Slack mrkdwn instead of a markdown block |
--list |
prints the configured webhook names |
By default the message is a markdown block: headings, lists, tables, links,
and fenced code all render. Use --plain for one-liners and :emoji:.
What it can't do
Read anything. A webhook is write-only, so there is no way to receive the user's reply here. If you need an answer:
- ask the question, then stop and wait for the user in this chat, or
- use the
slack-as-claudeskill (needs a bot token), which polls the thread.
Don't claim you'll "wait for their Slack reply" — you won't see it.
When to send
- Finishing long work, so the user doesn't have to keep checking.
- Blocking on a decision — send the question, then wait here.
- Failing in a way they need to know about now.
What ships with it
2 files 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.
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.
- 8d ago First seen · 90 lines · 59 tokens per session scan A f2e4a9a54f94
slack-webhook is a skill published in the GitHub repository tomeraitz/claude-slack-bridge (33 stars, last pushed 18d ago), licensed MIT. It adds 59 tokens to every session and 800 once invoked, about $0.0003 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.
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