Borrowing it
Nothing to install: this file belongs to aspenkit/aspens. 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/aspenkit/aspens/main/.agents/skills/agent-customization/SKILL.mdgit clone --depth 1 https://github.com/aspenkit/aspensWrote 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/aspenkit/aspens/agent-customization)<a href="https://agentmods.dev/skills/aspenkit/aspens/agent-customization"><img src="https://agentmods.dev/badge/skills/aspenkit/aspens/agent-customization/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/aspenkit/aspens/agent-customization"><img src="https://agentmods.dev/badge/skills/aspenkit/aspens/agent-customization.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 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 22 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 23 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 | $0.00022 | $0.00851 |
| Opus 5.5 | $0.00009 | $0.00340 |
| Sonnet 5.5 | $0.00004 | $0.00170 |
| Haiku 4.5 | $0.00002 | $0.00085 |
Grade A, and why
agent-customization 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 — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are working on agent customization — the feature that reads a project's skills and AGENTS.md, then uses Claude CLI to inject project-specific context into generic agent files in .claude/agents/.
Domain purpose
aspens customize agents makes generic, bundled agent templates project-aware. It pulls the repo's skills + AGENTS.md as ground truth and asks Claude to add a tech-stack line, 3-5 project conventions, and real commands into each agent — without touching the agent's core logic.
Business rules / invariants
- Claude-only feature. Throws
CliErrorfor Codex-only repos (config.targets === ['codex']). Codex CLI has no agent concept. - Base skill is required. Pre-flight throws
CliError("Run 'aspens doc init' first — base skill is required for agent context.")if.agents/skills/base/SKILL.mdis missing. - Skills (
.claude/skills/**) are the single source of truth for project context. The prompt must not invent other context directories. - Read-only tools only. Claude is invoked with
allowedTools: ['Read', 'Glob', 'Grep']— no edits/writes from the LLM itself. - Output paths restricted to
.claude/.parseFileOutput()rejects anything else;writeSkillFiles(..., { force: true })does the actual write.
Non-obvious behaviors
- Frontmatter preservation is split across LLM + code. The prompt instructs Claude to preserve YAML frontmatter verbatim (including NOT adding a
skills:line). ThenmaybeInjectBaseSkill()post-processes each returned file to addskills: [base]into the frontmatter — this keeps agents valid even when installed viaaspens add agentwithout a priordoc init. --resetsemantics: without--reset, agents that already declareskills:are left alone; with--reset, any existingskills:line is overwritten toskills: [base]. Used to roll out v0.8 upgrades to previously-customized agents.## Project contextblock is verbatim-preserved by the prompt — it carries conditional read instructions for code-map / domain skills.- AGENTS.md is truncated at 3000 chars in
gatherProjectContext(); skills are passed in full. - Agent discovery:
findAgents()recursively walks.claude/agents/, extractsname:via regex, falls back to filename if missing. - Default timeout 300s via
resolveTimeout(options.timeout, 300);ASPENS_TIMEOUTenv var honored with warning on invalid value.
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 · 47 lines · 22 tokens per session scan A 1a2600d50da9
agent-customization is a skill published in the GitHub repository aspenkit/aspens (103 stars, last pushed 1mo ago), licensed MIT. It adds 22 tokens to every session and 851 once invoked, about $0.0001 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.
Other skills, from other repositories
do
Work a SpecWeave increment task by task - claim, implement inside its Files, test, commit, done with evidence - alone, unattended or in lanes, then close. Use for "implement", "continue", "auto".
handoff
Hand work to another tool, account or machine and pick it up there, in two words. Use when the user says "hand off", "hand off all", "out of tokens", "switching accounts", "pick up" or "continue".
sw-do
Work a SpecWeave increment task by task - claim, implement inside its Files, test, commit, done with evidence - alone, unattended or in lanes, then close. Use for "implement", "continue", "auto".
sw-handoff
Hand work to another tool, account or machine and pick it up there, in two words. Use when the user says "hand off", "hand off all", "out of tokens", "switching accounts", "pick up" or "continue".
increment
Plan work as a SpecWeave increment - one spec.md with Problem, Scope, numbered ACs, Approach and Tasks - before writing code. Use for "plan a feature", "new increment", "let's build X".
review
Adversarial review of an increment before it ships, by a fresh context or another model family; every finding cites path:line and is re-verified. Use for "review", "qa", "critique this".