develop-from-spec

A specification-led workflow for substantial software changes, covering discovery, written specifications, planning, approval, implementation, and verification.

In plain words
What is it for?
Use it to investigate a feature, write its design and implementation plan, obtain approval, make the change, run checks, and record evidence.
Why use it?
It reduces the risk of coding the wrong thing by requiring the work to be understood and approved before implementation.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/gabonio/agent-operator-toolkit/develop-from-spec
Any agent
npx skills add gabonio/agent-operator-toolkit --skill develop-from-spec
Clone the repo
git clone --depth 1 https://github.com/gabonio/agent-operator-toolkit

Made for: Claude Code, Codex.

Per session 66 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 466 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00066 $0.00466
Opus 5 $0.00033 $0.00233
Sonnet 5 $0.00013 $0.00093
Haiku 4.5 $0.00007 $0.00047

Measured 2d ago against content hash e367e0c0cc03, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

develop-from-spec 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 2d 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.

plugins/builder-kit/skills/develop-from-spec/SKILL.md · 25 lines

How it starts

The opening of the file, as written. The whole thing — 25 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Develop from Spec

Workflow

  1. Discover. Read local instructions, relevant architecture/design documents, neighboring code and tests, build/delivery rules, and sources of truth. Load only matching references and lenses.
  2. Specify. Follow the repository's document convention. If none exists, propose docs/specs/YYYY-MM-DD-<feature>-design.md. Use the specification workflow and the template.
  3. Approve the specification. For large or high-risk work, stop for this approval before writing the implementation plan.
  4. Plan. Follow the repository convention or propose docs/plans/YYYY-MM-DD-<feature>-implementation.md. Use the plan template. Make it literal enough for a faster executor without duplicating the specification.
  5. Approve the plan. Stop before implementation until the user unambiguously approves. Bounded features may receive combined specification-and-plan approval.
  6. Execute. Follow ordered checkboxes, preserve unrelated work, make the smallest approved change, and record evidence. Ask for renewed approval on material drift.
  7. Verify. Run focused checks while iterating and the closest local production-like build before PR readiness. Report exact evidence and unresolved risk.

Material drift

Stop for renewed approval before changing scope, acceptance criteria, architecture, public behavior, data/API contracts, dependencies, security or authorization boundaries, migrations, or deployment behavior. Small implementation details may change when they preserve the approved design; record meaningful deviations.

Executor handoff

The implementation plan is the handoff. Do not create a third summary. The executor follows concrete decisions, contracts, constraints, tests, stop conditions, and commands—not persona prompts or lens names. Recommend planning and execution capabilities using model profiles, not a permanently pinned model name.

Read the full file on GitHub · 25 lines

Files

What ships with it

1 file 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.

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. 2d ago First seen · 25 lines · 66 tokens per session scan A e367e0c0cc03

Subscribe to this mod's changes

develop-from-spec is a skill published in the GitHub repository gabonio/agent-operator-toolkit (1 stars, last pushed 28d ago), licensed MIT. It adds 66 tokens to every session and 466 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 2026-08-31.

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