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 skills/alleneubank/claude-code/spec-best-practicesnpx skills add alleneubank/claude-code --skill spec-best-practicesgit clone --depth 1 https://github.com/alleneubank/claude-codeWrote 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/alleneubank/claude-code/spec-best-practices)<a href="https://agentmods.dev/skills/alleneubank/claude-code/spec-best-practices"><img src="https://agentmods.dev/badge/skills/alleneubank/claude-code/spec-best-practices.svg" alt="Measured on agentmods" 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 | $0.00031 | $0.00933 |
| Opus 5 | $0.00015 | $0.00466 |
| Sonnet 5 | $0.00006 | $0.00187 |
| Haiku 4.5 | $0.00003 | $0.00093 |
Grade A, and why
spec-best-practices 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 4d 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 — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Naming
Always SPEC.md. No exceptions for the primary spec file. Not feature.spec.md, not SPEC-feature.md.
Supporting documents linked from a SPEC.md TOC may use descriptive names (e.g., commands.spec.md), but only when a root SPEC.md exists and links to them.
Placement
Specs are colocated with the code they describe: root SPEC.md for project scope, apps/foo/SPEC.md for app scope, packages/bar/SPEC.md for package scope.
- Avoid
spec/,docs/specs/, anddocs/plans/directories. Prefer colocatedSPEC.mdfiles. - Plan documents are ephemeral. Absorb durable decisions into the relevant
SPEC.mdand delete the plan doc. - When a spec gets long, add a TOC linking to adjacent supporting files (
./commands.spec.md, etc.). Supporting files live alongside theSPEC.md, not in a subdirectory.
Content
Specs are freeform markdown. No rigid template, no YAML frontmatter, no required section ordering. These elements must be present:
Problem and solution -- narrative context for why this system/feature exists. Lead with the problem.
Domain model -- types, relationships, data flow. For retroactive specs, derive from inspected code.
Requirements with REQ-* IDs -- every behavioral requirement gets a stable identifier. Format: REQ-{DOMAIN}-{NNN} (e.g., REQ-AUTH-001). Append-only; never renumber. Each requirement is testable and traceable.
Invariants -- conditions that must always hold.
Non-goals -- explicit scope boundary. What this spec intentionally does not cover.
Acceptance criteria -- markdown checklist, not prose:
- [ ] Auth endpoint returns JWT with tier claim
- [ ] Rate limiter rejects >100 req/min per IP
Risk tags (conditional) -- flag high-risk items (schema migrations, auth changes, public API contracts, infra changes) when those risks exist or the ADF PLAN gate requires approval.
Test traceability (conditional) -- REQ-* to test file:line mapping. Added during/after TDD, not at initial authoring.
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.
- 4d ago First seen · 64 lines · 31 tokens per session scan A ee93094cd5b8
spec-best-practices is a skill published in the GitHub repository alleneubank/claude-code (52 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 31 tokens to every session and 933 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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