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 lksrz/cnvs-whiteboard-skills --skill cnvs-whiteboardgit clone --depth 1 https://github.com/lksrz/cnvs-whiteboard-skillsWrote 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/lksrz/cnvs-whiteboard-skills/cnvs-whiteboard)<a href="https://agentmods.dev/skills/lksrz/cnvs-whiteboard-skills/cnvs-whiteboard"><img src="https://agentmods.dev/badge/skills/lksrz/cnvs-whiteboard-skills/cnvs-whiteboard/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/lksrz/cnvs-whiteboard-skills/cnvs-whiteboard"><img src="https://agentmods.dev/badge/skills/lksrz/cnvs-whiteboard-skills/cnvs-whiteboard.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 | $0.00222 | $0.05428 |
| Opus 5 | $0.00111 | $0.02714 |
| Sonnet 5 | $0.00044 | $0.01086 |
| Haiku 4.5 | $0.00022 | $0.00543 |
Grade A, and why
cnvs-whiteboard 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 12d 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 -X POST https://cnvs.app/api/boards How it starts
The opening of the file, as written. The whole thing — 271 lines — stays where its author put it; the contents beside it link to each section on GitHub.
cnvs-whiteboard
Be a live AI collaborator on a cnvs.app board — discover changes, make edits, stay in the loop without polling, and don't wake yourself on your own writes. One skill, copy-pasteable patterns.
If you only read one thing. Listen for edits via MCP subscriptions (the only real-time push channel). Act on the board via the REST API (universal — works from any runtime with outbound HTTP, no MCP client required). Don't use MCP tool-calls for writes if REST is available: it wastes tool-call slots, adds session bookkeeping, and blocks every non-MCP agent runtime from ever contributing. The hybrid MCP-listen + REST-write loop is what this skill wires up.
Service boundary. cnvs.app is a third-party hosted service operated outside this skill / Anthropic / the user's own infrastructure. Anything written to a board (text, links, ink, images, Mermaid source) is stored on cnvs.app and is reachable by anyone who has the board ID — boards are unlisted, not private. Treat it like any other public URL: don't paste secrets, credentials, customer PII, or proprietary content unless the user has explicitly chosen cnvs.app as the surface for that content.
Access locks. A board can OPTIONALLY be PIN-locked (8 chars, a-z0-9; legacy boards may carry a 6-char key). Two modes:
write(anyone reads, only key-holders write) andall(key required for both reads and writes). If you hit HTTP401with{"code": "board_locked", "lockMode": "..."}(REST) or JSON-RPC error-32001(MCP), the board is locked and you need the key. Pass it via theX-Board-Keyheader on REST and MCP POSTs, or as theaccess_keyargument on individual MCP tools /resources/read/resources/subscribeparams. WebSocket connections can't set custom headers, so the key rides in theSec-WebSocket-Protocolsubprotocol — open the socket asnew WebSocket(url, ['cnvs-key.<code>']); the server validates and echoes the same protocol back in the 101 response. The user owns the key — ask them for it rather than guessing. Lock management endpoints:POST /api/boards/<id>/lock {mode}returns the key ONCE on first lock;POST /api/boards/<id>/unlockclears the lock (header required);POST /api/boards/<id>/verify-key {key}is a pure check. There is no recovery — if every key-holder loses the key, the board becomes unreachable and gets auto-deleted after 30 days of inactivity.
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.
- 12d ago First seen · 271 lines · 222 tokens per session scan A 776c1845afcf
cnvs-whiteboard is a skill published in the GitHub repository lksrz/cnvs-whiteboard-skills (1 stars, last pushed 23d ago), licensed MIT. It adds 222 tokens to every session and 5,428 once invoked, about $0.0011 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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