spec-planning

spec-planning is a skill for Claude Code, Codex from byerlikaya/claude-starter-kit. It costs 51 tokens per session (770 once invoked), scanned A, original, MIT.

A planning guide for turning an unclear or multi-part coding request into an ordered specification.

In plain words
What is it for?
Use it to define scope, split work into end-to-end pieces, write measurable acceptance criteria, and record assumptions in docs/PLAN.md.
Why use it?
It makes the meaning of “done,” task dependencies, risks, and unanswered questions explicit before coding begins.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Claude Code.

Good fit Use it to define scope, split work into end-to-end pieces, write measurable acceptance criteria, and record assumptions in docs/PLAN.md.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/byerlikaya/claude-starter-kit/spec-planning
Install

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.

Any agent
npx skills add byerlikaya/claude-starter-kit --skill spec-planning
Clone the repo
git clone --depth 1 https://github.com/byerlikaya/claude-starter-kit

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for spec-planning

README.md
[![agentmods](https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/spec-planning/github.svg)](https://agentmods.dev/skills/byerlikaya/claude-starter-kit/spec-planning)
Your own site
<a href="https://agentmods.dev/skills/byerlikaya/claude-starter-kit/spec-planning"><img src="https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/spec-planning/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.

agentmods 80×15 button for spec-planning

Your own site · 80×15
<a href="https://agentmods.dev/skills/byerlikaya/claude-starter-kit/spec-planning"><img src="https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/spec-planning.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 770 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

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 →

  • high Prompt Injection · line 11
    Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.
    Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00051 $0.00770
Opus 5 $0.00026 $0.00385
Sonnet 5 $0.00010 $0.00154
Haiku 4.5 $0.00005 $0.00077

Measured 11d ago against content hash afd60bd498f2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

spec-planning 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 11d 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.

claude-starter/skills/spec-planning/SKILL.md · 57 lines

How it starts

The opening of the file, as written. The whole thing — 57 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec-First Planning

Trigger phrases: "plan", "spec", "task breakdown", "acceptance criteria", "roadmap", "how do we split this"

Before writing code: what will be done, how it counts as "done", and in what order to proceed become clear.

Steps

  1. Purpose & scope: the problem being solved in a single sentence; also write the out-of-scope explicitly (prevent scope creep).
  2. Split into vertical slices: the smallest end-to-end working pieces (not horizontal layers). Each slice delivers value on its own.
  3. A contract for every task: input · output · measurable acceptance criterion (testable) · estimated risk.
  4. Dependency graph: which task waits on what; no cycles. Bring the riskiest/most-unknown to the front (fail-fast).
  5. Uncertainties: assumption list + open questions; do not fill ambiguous spots with a guess, ask with explicit options.

Output (docs/PLAN.md)

# <Feature> — Plan
## Acceptance criteria
- [ ] <measurable outcome>
## Tasks (order)
1. <task> — criterion: <...> — dependency: <none/#n> — risk: <low/medium/high>
## Assumptions / Open questions
- ...

Mark what you do not know — do not fill it in

Where a requirement admits more than one reading, write the marker [NEEDS CLARIFICATION: <the question>] at that exact spot in the plan. Do not resolve it with the likeliest interpretation and move on.

This is the difference between a discipline and a hope. "Stop and ask when unsure" (§1) depends on noticing the uncertainty in the moment; a marker survives into the artifact, where the user, a reviewer and a later session can all see it. A plausible assumption silently written into a spec is indistinguishable from a decision, and that is exactly how the wrong feature gets built correctly.

Read the full file on GitHub · 57 lines

Changes

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.

  1. 11d ago First seen · 57 lines · 51 tokens per session scan A afd60bd498f2

Subscribe to this mod's changes

spec-planning is a skill published in the GitHub repository byerlikaya/claude-starter-kit (22 stars, last pushed today), licensed MIT. It adds 51 tokens to every session and 770 once invoked, about $0.0003 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.

Related

Other skills, from other repositories

security-compliance

Guides security professionals in implementing defense-in-depth security architectures, achieving compliance with industry frameworks (SOC2, ISO27001, GDPR, HIPAA), conducting threat modeling and risk assessments, managing security operations and incident response, and embedding security throughout the SDLC.

sangrokjung/claude-forge · 56 tokens

stride-analysis-patterns

Apply STRIDE methodology to systematically identify threats. Use when analyzing system security, conducting threat modeling sessions, or creating security documentation.

sangrokjung/claude-forge · 30 tokens

review-loop

Run the adversarial verification loop — implement, then hand the change to a fresh checker that did not write it, fix what it finds, and re-dispatch until APPROVE. Use before claiming any behavioural change is done, and on requests like "review loop", "adversarial review", "independent review", "get this verified"…

sangrokjung/claude-forge · 100 tokens

prompts-chat

Use when searching, installing, or improving AI skills and prompts via prompts.chat or skills.sh. Triggers on skill search, prompt lookup, install skill, improve prompt, prompts.chat.

sangrokjung/claude-forge · 41 tokens

writing-fragments

Grilling session that mines the user for fragments — heterogeneous nuggets of writing (claims, vignettes, sharp sentences, half-thoughts) — and appends them to a single document as raw material for a future article. Use when the user wants to develop ideas before imposing structure, or mentions "fragments", "ideate"…

stevesolun/ctx · 80 tokens

caveman-help

Quick-reference card for all caveman modes, skills, and commands. One-shot display, not a persistent mode. Trigger: /caveman-help, "caveman help", "what caveman commands", "how do I use caveman".

stevesolun/ctx · 56 tokens