Borrowing it
Nothing to install: this file belongs to chrzanowy/agent-tollbooth. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/chrzanowy/agent-tollbooth/main/.claude/skills/checkpoint/SKILL.mdgit clone --depth 1 https://github.com/chrzanowy/agent-tollboothWrote 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/chrzanowy/agent-tollbooth/checkpoint)<a href="https://agentmods.dev/skills/chrzanowy/agent-tollbooth/checkpoint"><img src="https://agentmods.dev/badge/skills/chrzanowy/agent-tollbooth/checkpoint/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.
<a href="https://agentmods.dev/skills/chrzanowy/agent-tollbooth/checkpoint"><img src="https://agentmods.dev/badge/skills/chrzanowy/agent-tollbooth/checkpoint.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00062 | $0.00606 |
| Opus 5 | $0.00031 | $0.00303 |
| Sonnet 5 | $0.00012 | $0.00121 |
| Haiku 4.5 | $0.00006 | $0.00061 |
Grade A, and why
checkpoint scanned grade A with 1 finding 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 9d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -s localhost:4402/board/open -H 'content-type: application/json' \ How it starts
The opening of the file, as written. The whole thing — 55 lines — stays where its author put it; the contents beside it link to each section on GitHub.
checkpoint — save durable context to the board, on demand
Post ONE entry to the shared tollbooth board capturing what a future session (or a different agent) must know to continue this work without re-reading the transcript. This is invoked deliberately — do not checkpoint on your own schedule; narration belongs in the transcript, which is captured for free.
Steps
-
Find the board. Derive the topic deterministically from the work:
repo:<host>/<owner>/<name>is the project inbox; a distinct workstream within the project gets its own board atrepo:<host>/<owner>/<name>/ctx:<slug>. Checkpoint to the workstream board when this session's work belongs to one; default to the inbox. Open it (get-or-create), passing a one-linedescriptionwhen the board might be new — it is what future warmstart menus display:curl -s localhost:4402/board/open -H 'content-type: application/json' \ -d '{"topic":"repo:github.com/owner/name/ctx:auth-refactor","description":"auth refactor workstream"}'Or the MCP tool
board_openif available. -
Read before writing.
GET /board/<id>(orboard_read) — see what the latest digest and recent entries already cover. Never repeat what is already on the board. -
Post one entry (
board_post), 5–15 lines, containing ONLY:- decisions made this session, each with its one-line why
- dead ends ruled out (so nobody re-explores them)
- constraints or facts discovered that no file records
- the exact next action, concrete enough to start cold
- unresolved questions blocking that action, if any
Set
authorhonestly:{"name":"<role>","model":"<your model>","harness":"<your harness>"}.
What NOT to include
Progress narration ("then I ran the tests"), anything the repo or git history records, code that exists in files, praise or hedging. Every line must be something a cold-started agent would otherwise have to rediscover at token cost.
Cost discipline
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.
- 9d ago First seen · 55 lines · 62 tokens per session scan A 6b120075eb43
checkpoint is a skill published in the GitHub repository chrzanowy/agent-tollbooth (0 stars, last pushed 24d ago), licensed MIT. It adds 62 tokens to every session and 606 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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