Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/existential-birds/beaglenpx agentmods add skills/existential-birds/beagle/write-planWrote 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/existential-birds/beagle/write-plan)<a href="https://agentmods.dev/skills/existential-birds/beagle/write-plan"><img src="https://agentmods.dev/badge/skills/existential-birds/beagle/write-plan/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/existential-birds/beagle/write-plan"><img src="https://agentmods.dev/badge/skills/existential-birds/beagle/write-plan.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 3 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Agent Snooping · line 48 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
- medium Agent Snooping · line 419 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
- medium Agent Snooping · line 428 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 | $0.00170 | $0.09107 |
| Opus 5.5 | $0.00068 | $0.03643 |
| Sonnet 5.5 | $0.00034 | $0.01821 |
| Haiku 4.5 | $0.00017 | $0.00911 |
Grade A, and why
write-plan 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 1mo 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 — 460 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Write Plan: Spec Into Implementation Plan
Turn a brainstorm-beagle spec into a comprehensive implementation plan that an engineer (or a downstream agent) can execute task-by-task without re-deriving intent.
The output is a single markdown plan document at .beagle/concepts/<slug>/plan.md, sitting beside the spec in the same concept folder. The plan captures HOW — file structure, task decomposition, exact code, exact commands — while the spec already owns WHAT and WHY.
<hard_gate>
Do NOT start writing the plan until a brainstorm-beagle spec exists at .beagle/concepts/<slug>/spec.md. If one is missing, stop and route the user to brainstorm-beagle first. Skipping the spec produces plans that bake in unexamined assumptions — the spec is the contract this skill plans against.
</hard_gate>
Workflow
Complete these steps in order:
- Locate the spec — find
.beagle/concepts/<slug>/spec.md; if absent, stop and route to brainstorm-beagle - Read the spec — ingest every section; do not paraphrase, do not summarize away requirements
- Read project conventions — scan project conventions (e.g. AGENTS.md or CLAUDE.md, root and nested) for testing, commenting, and architecture rules the plan must respect
- Explore relevant code — read existing files the plan will touch or pattern-match against; do not guess at structure
- Design file structure — map which files will be created or modified before any task is written
- Decompose into tasks — each task is bite-sized (2-5 minute steps), TDD-driven, with exact paths and code
- Self-review — check against the spec, scan for placeholders, verify type consistency (see Self-Review below)
- Optionally run a reviewer pass — only for plans that are long or cover unfamiliar territory. If the agent supports subagents, dispatch a reviewer subagent; otherwise run the same review inline — identical output (see
references/plan-reviewer.md) - Present draft to user — show the draft in chat for review; iterate if needed
- Write to disk — save to
.beagle/concepts/<slug>/plan.mdonly after explicit user approval
What ships with it
2 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.
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.
- 1mo ago First seen · 460 lines · 170 tokens per session scan A 1b8732226b6b
write-plan is a skill published in the GitHub repository existential-birds/beagle (84 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 170 tokens to every session and 9,107 once invoked, about $0.0007 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 2026-08-30.
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