Testing vs Docs & Writing · both proven

writing-guidelines vs writing-plans

Both skills were run through Claude twice: once on a fixed brief without the skill, once with it. The briefs differ because each is written for the job the skill claims to do, so compare each skill against its own baseline, then decide which difference matters for your work. They are in different categories, so this is a choice of job, not a head-to-head on the same job.

writing-guidelines

Review docs/prose for Writing Guidelines compliance. Use when asked to "review my docs", "check writing style", "audit prose", "review docs voice and tone", or "check this page against the writing handbook".

Category: Testing
Source: vercel-labs/agent-skills
License: Not stated
Proof model: claude-opus-5-5
Brief: “Review and rewrite this getting-started page for Pipewell, a data pipeline CLI. The draft opens with two paragraphs of company history, mixes 'you' and 'the user', buries the install command in the fourth paragraph, uses passive voice throughout, and ends without a next step. Write the improved page as a single HTML document, followed by a short list of what you changed and why.”
Skill commit: 063bee9

Without the skillWith writing-guidelines

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Without, runWith writing-guidelines, run3 independent runs per side, none selected by hand.

Download the with-skill page

writing-plans

Use when you have a spec or requirements for a multi-step task, before touching code

Category: Docs & Writing
Source: obra/superpowers
License: MIT
Proof model: claude-opus-5-5
Brief: “Write the implementation plan for adding team accounts to a solo-user invoicing SaaS (Next.js, Postgres, Stripe): users must be able to create a team, invite members by email, assign owner or member roles, and share clients and invoices within the team, with billing moving from the user to the team. Present the plan as a single HTML page.”
Skill commit: bb92a77

Without the skillWith writing-plans

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Without, runWith writing-plans, run3 independent runs per side, none selected by hand.

Download the with-skill page

We don’t pick a winner for you: the pages are the evidence. Both proofs can be repeated with the brief, model and commit shown above. See alternatives to writing-guidelines or alternatives to writing-plans.