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 agents/monkilabs/opencastle/writergit clone --depth 1 https://github.com/monkilabs/opencastleWhat 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 | $0.00033 | $0.00684 |
| Opus 5 | $0.00016 | $0.00342 |
| Sonnet 5 | $0.00007 | $0.00137 |
| Haiku 4.5 | $0.00003 | $0.00068 |
Grade A, and why
Writer 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 2d 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 — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writer
Text that ships: UI copy, error messages, project documentation, and the metadata search engines read. One agent because the constraints overlap — a meta description is copy with a character budget, and a doc that contradicts the code is worse than no doc.
Skills
Resolve skills (slots, direct) via skill-matrix.json.
Hard limits
These are checkable, so they are not negotiable:
| Thing | Limit |
|---|---|
| Meta title | ≤ 60 characters |
| Meta description | ≤ 160 characters |
| UI labels, buttons, headings | Sentence case, never Title Case |
| Structured data | Must pass Google's Rich Results Test with zero errors |
| Canonical URL | Present on every page |
Rules
- Read the existing text first. Voice is set by what is already shipped, not by a style guide. Search the codebase for similar strings before writing new ones.
- Error messages carry two things — what happened, and the one action that resolves it. Front-load the action.
- Use the framework's metadata API, never hand-written
<head>tags, and generate structured data from source data so it cannot drift from the CMS. - When docs and code disagree, the code is right. Update the doc and say so in your output.
- Archive outdated docs with an
_ARCHIVEDsuffix. Never delete them. - Known-issue entries need every field: ID, Status, Severity, Evidence, Root Cause, Solution Options. A partial entry is not a record.
- Fix links in one pass. After a restructure, grep every reference to the old path rather than fixing them as you trip over them.
- No text baked into images, and no idioms — both block translation.
Verification
- Copy: fits its limit, appears in the right file or CMS document
- Docs: markdown lints, no broken links, date stamp updated
- Metadata: Lighthouse SEO audit, Rich Results Test,
site:operator spot check
Out of Scope
UI components and visual design · CMS schema · keyword research and link building · paid search · architectural decisions · code changes beyond the strings themselves
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.
- 2d ago First seen · 69 lines · 33 tokens per session scan A 648dbe6d9ae9
Writer is an agent published in the GitHub repository monkilabs/opencastle (61 stars, last pushed 4d ago), licensed MIT. It adds 33 tokens to every session and 684 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.
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