Design vs Frontend · both proven

mcp-builder vs vercel-react-best-practices

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.

mcp-builder

Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).

Category: Design
Source: anthropics/skills
License: Not stated
Proof model: claude-opus-5-5
Brief: “Build an MCP server in TypeScript that gives an agent read access to a team's Linear-style issue tracker through a REST API: tools to search issues, get one issue with comments, and list a project's open issues by priority. Present it as a single HTML page with the full source of each file, the tool schemas, how errors and pagination are handled, and how to run and connect it.”
Skill commit: dbd4588

Without the skillWith mcp-builder

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Without, runWith mcp-builder, run3 independent runs per side, none selected by hand.

Download the with-skill page

vercel-react-best-practices

React and Next.js performance optimization guidelines from Vercel Engineering. This skill should be used when writing, reviewing, or refactoring React/Next.js code to ensure optimal performance patterns. Triggers on tasks involving React components, Next.js pages, data fetching, bundle optimization, or performance improvements.

Category: Frontend
Source: vercel-labs/agent-skills
License: Not stated
Proof model: claude-opus-5-5
Brief: “Here is a slow Next.js product list page. It fetches products, reviews and inventory one after another in a client component with useEffect, renders 500 product cards at once, imports the full lodash library, and re-sorts the list on every render. Rewrite it following current React and Next.js performance practice, and present the result as a single HTML page that shows the new code, explains each change, and estimates the impact of each.”
Skill commit: 063bee9

Without the skillWith vercel-react-best-practices

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Without, runWith vercel-react-best-practices, 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 mcp-builder or alternatives to vercel-react-best-practices.