A periodic checklist for checking reminders, ongoing tasks, time-sensitive events, and unanswered questions. It reports only items that need attention.

Use it for scheduled background checks of reminders, task lists, deadlines, events, and pending user decisions.

It helps surface useful follow-ups without filling the user’s updates with routine status messages.

heartbeat — Skill for Claude Code and Codex by desy-design

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 desy-design/AG3NT --skill heartbeat

Clone the repo

git clone --depth 1 https://github.com/desy-design/AG3NT

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/desy-design/ag3nt/heartbeat/github.svg)](https://agentmods.dev/skills/desy-design/ag3nt/heartbeat)

Your own site

<a href="https://agentmods.dev/skills/desy-design/ag3nt/heartbeat"><img src="https://agentmods.dev/badge/skills/desy-design/ag3nt/heartbeat/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/desy-design/ag3nt/heartbeat"><img src="https://agentmods.dev/badge/skills/desy-design/ag3nt/heartbeat.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 10 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 340 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 100% copy Near-identical to another mod 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	$0.00010	$0.00340
Opus 5	$0.00005	$0.00170
Sonnet 5	$0.00002	$0.00068
Haiku 4.5	$0.00001	$0.00034

Measured 8d ago against content hash 9b565fcfca2e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

heartbeat 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.

Origin

This is a copy

100% identical to heartbeat — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/heartbeat/SKILL.md · 52 lines

What it actually says

Heartbeat Check

You are running a scheduled periodic check. Go through this checklist and only report items that need the user's attention.

Checklist

Pending reminders: Check if any scheduled reminders are due or approaching
Task status: Review any in-progress tasks in your todo list that need attention
Time-sensitive items: Note upcoming events or deadlines if known
Pending questions: Check if there are any unresolved questions waiting for user input

Response Format

If there is something to report, provide a brief summary of what needs attention
If nothing needs attention, respond ONLY with: HEARTBEAT_OK

Guidelines

Be concise: Only report actionable items
Prioritize: Most urgent items first
No noise: If in doubt, say HEARTBEAT_OK
No greetings: Skip pleasantries, get to the point

Example Responses

Nothing to report:

HEARTBEAT_OK

Has items to report:

📋 Quick update:
- Reminder: Call Alice at 3pm (in 30 minutes)
- Task: Code review for PR #42 is still pending

Important: This is a background check. Only surface genuinely useful information. The user should not be bothered by empty or low-value notifications.

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.

8d ago First seen · 52 lines · 10 tokens per session scan A 9b565fcfca2e

Subscribe to this mod's changes

heartbeat is a skill published in the GitHub repository desy-design/AG3NT (2 stars, last pushed yesterday), licensed MIT. It adds 10 tokens to every session and 340 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to heartbeat, differing in 0 lines, and is treated as a copy.

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heartbeat