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 agentmods add skills/monkilabs/opencastle/slacknpx skills add monkilabs/opencastle --skill slackgit clone --depth 1 https://github.com/monkilabs/opencastleWrote 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/monkilabs/opencastle/slack)<a href="https://agentmods.dev/skills/monkilabs/opencastle/slack"><img src="https://agentmods.dev/badge/skills/monkilabs/opencastle/slack.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00041 | $0.00532 |
| Opus 5 | $0.00020 | $0.00266 |
| Sonnet 5 | $0.00008 | $0.00106 |
| Haiku 4.5 | $0.00004 | $0.00053 |
Grade A, and why
slack-notifications 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 4d 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.
What it actually says
Slack Notifications
Package @kazuph/mcp-slack (stdio). Docs: https://api.slack.com/docs. Channel mappings: .opencastle/stack/notifications-config.md
Setup
SLACK_MCP_XOXB_TOKEN— bot token, stored in CI/env, rotated periodically.SLACK_MCP_ADD_MESSAGE_TOOL=trueis required to post at all — write support is off by default.- Minimal bot scopes for notifications:
chat:write,channels:read,conversations:history,users:read. Read-only:channels:read,channels:history,im:read.
Rate limits
Write 20/min, read 50/min. Batch updates instead of per-step chatter, thread rather than posting new messages, and cache channel/user IDs — repeated users_resolve lookups burn the read budget.
Tools
conversations_add_message—channel_id,payload,content_type,thread_tsconversations_history—channel_id,limitconversations_replies—channel_id,thread_ts,limitusers_resolve—email|username
Check the response for ok; a failed post returns error rather than throwing.
Approvals are dual-channel
Post to Slack and ask in chat. First response wins.
- Post
⏳ Approval Required — TAS-42: <action>with reply instructions, keeping the returnedthread_ts. - Ask the same question in chat. A chat answer wins → post the confirmation into the Slack thread.
- Otherwise poll
conversations_replieson that thread every 30s, timing out at 10 min, matching approved/yes/go vs rejected/no/stop. - If the session ends before a reply, write a checkpoint with channel, thread ID, question, and timestamp. The next session's
on-session-starthook picks up the reply.
Always thread; one thread per task; include the tracker issue ID in every message. Never put secrets in a message body.
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.
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.
- 4d ago First seen · 41 lines · 41 tokens per session scan A 0347404812cc
slack-notifications is a skill published in the GitHub repository monkilabs/opencastle (61 stars, last pushed 6d ago), licensed MIT. It adds 41 tokens to every session and 532 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 2026-08-30.
Other skills, from other repositories
product-architect
Complete product development system with 80 agents and 36 frameworks. Use when the user wants to build a product, write a PRD, plan an MVP or roadmap, design an app, research a market or check whether a feature already exists or is novel, do competitive analysis, run a security audit, build a financial model, plan…
codex-delegation
Use when a coding task would benefit from delegating work to Codex in the background — a deep independent second opinion, security or architecture analysis, or a parallel implementation running while the session continues. Lets Claude drive the codex companion itself (task, review, status --wait, result) without the…
cursor-delegation
Use when a coding task would benefit from delegating work to Cursor in the background — fast parallel implementation, scaffolding, or an everyday review running while the session continues. Lets Claude drive the cursor companion itself (task, review, status --wait, result) without the user typing /cursor: commands.
cursor-cli-runtime
Internal helper contract for calling the cursor-companion runtime from Claude Code.
cursor-prompting
Internal guidance for composing cursor-agent prompts and picking models for coding, review, diagnosis, and research tasks inside the Cursor Claude Code plugin.
goal-runner
Use when the user asks to advance, continue, or work on the project's long-horizon goal (or to set one up) — the policy for goal-driven increments driven through the goal companion, one increment at a time, delegated via the codex/cursor delegation skills, honestly recorded.