Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add richfrem/agent-plugins-skills/plugin install agent-extension-authoringWrote 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/richfrem/agent-plugins-skills/authoring-instructions)<a href="https://agentmods.dev/skills/richfrem/agent-plugins-skills/authoring-instructions"><img src="https://agentmods.dev/badge/skills/richfrem/agent-plugins-skills/authoring-instructions/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/richfrem/agent-plugins-skills/authoring-instructions"><img src="https://agentmods.dev/badge/skills/richfrem/agent-plugins-skills/authoring-instructions.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 | $0.00120 | $0.01097 |
| Opus 5.5 | $0.00048 | $0.00439 |
| Sonnet 5.5 | $0.00024 | $0.00219 |
| Haiku 4.5 | $0.00012 | $0.00110 |
Grade A, and why
authoring-instructions scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 68 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Authoring Instructions (authoring-instructions)
Writes lean, invariant-driven instruction files and audits them deterministically: rules, root AGENTS.md / CLAUDE.md, and plugin hooks.
Contents
- Constraints • Modes • Quick start • Workflow • Verification • References
Constraints
- Rules are constraints, skills are procedures. A rule states MUST / NEVER / ALWAYS bounds in 30–70 lines (ceiling 80); anything with ordered steps becomes a skill.
- Timeless and portable: no calendar dates, commit SHAs, usernames or absolute machine paths in a rule or root file.
- Never overwrite an existing
AGENTS.mdorCLAUDE.md; propose a diff.CLAUDE.mdstays a bridge of 5 lines or fewer. - Audits are read-only. They report findings; changes are reviewed edits.
- Hooks use
python3 ... || python ...commands anchored on${CLAUDE_PLUGIN_ROOT}, exit silently when the repository is not initialised, and stay fast. - APM does not deploy a plugin's
rules/folder (instructions deploy from.apm/instructions/), so rules need no link or registration step.
Modes
| Mode | Use when | Entry point | Reference |
|---|---|---|---|
create-rule |
New rule file | write the canonical structure | create-rule.md |
audit-rule |
Check rules | scripts/audit_rule.py |
audit-rule.md |
create-agents-md |
Scaffold or migrate root files | assets/templates/AGENTS.md.jinja |
create-agents-md.md |
audit-agents-md |
Check size, timelessness, disclosure | scripts/audit_agents_md.py |
audit-agents-md.md |
hook |
Add, lint or test a lifecycle hook | scripts/scaffold_hook.py |
create-hook.md |
Quick start
python3 scripts/audit_rule.py <rules-dir-or-file> --json
python3 scripts/audit_agents_md.py AGENTS.md --strict
python3 scripts/scaffold_hook.py --event PreToolUse --name check-command --plugin-root plugins/<plugin>
What ships with it
22 files 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.
- assets/templates/AGENTS.md.jinja 687 B
- evals/evals.json 3.3 KB
- references/acceptance-criteria.md 2.3 KB
- references/agents-md-contract.md 3.6 KB
- references/fallback-tree.md 2.2 KB
- references/hook-advanced.md 11 KB
- references/hook-migration.md 8.7 KB
- references/hook-patterns.md 7.7 KB
- references/hooks-spec.md 4.3 KB
- references/modes/audit-agents-md.md 2.2 KB
- references/modes/audit-rule.md 2.4 KB
- references/modes/create-agents-md.md 2.7 KB
- references/modes/create-hook.md 2.9 KB
- references/modes/create-rule.md 3.3 KB
- scripts/audit_agents_md.py 15 KB runs code
- scripts/audit_rule.py 12 KB runs code
- scripts/hook_linter.py 7.1 KB runs code
- scripts/scaffold_hook.py 3.7 KB runs code
- scripts/test_hook.py 10.0 KB runs code
- scripts/validate_hook_schema.py 8.5 KB runs code
- scripts/validate_write.py 2.9 KB runs code
- tests/test_hooks.py 3.3 KB runs code
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.
- today First seen · 68 lines · 120 tokens per session scan A 26bdc2593cf0
authoring-instructions is a skill published in the GitHub repository richfrem/agent-plugins-skills (7 stars, last pushed yesterday), licensed MIT. It adds 120 tokens to every session and 1,097 once invoked, about $0.0005 per session on Opus 5.5. 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 2026-10-24.
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