Skills mcp-builder

📦

mcp-builder

Name: mcp-builder
Author: mcp-use

Low Risk ⚙️ External commands

Build MCP Servers

Also available from: 92Bilal26,92Bilal26,ArtemisAI,anthropics,Azeem-2,ZhanlinCui,AutumnsGrove,Doyajin174,DYAI2025,YYH211,Cam10001110101,ComposioHQ,davila7

This skill helps developers create Model Context Protocol servers with tools, resources, prompts, and interactive widgets using the mcp-use framework. Note: This skill is deprecated; use mcp-app-builder instead.

Supports: Claude Codex Code(CC)

🥉 72 Bronze

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Test it

Using "mcp-builder". Create an MCP tool that translates text between languages

Expected outcome:

Server tool definition with translate function calling external API, returning text response using response helper

Using "mcp-builder". Build a weather widget with city search

Expected outcome:

React component with weather-display.tsx, widgetMetadata with props schema, and matching tool configuration

Security Audit

Low Risk

v1 • 2/22/2026

All 442 static findings are false positives. The skill is a legitimate MCP server builder framework (deprecated). Findings appear in documentation/reference files showing code examples. The 'weak crypto' alerts are triggered by `.describe()` method (Zod), 'external commands' by markdown code fences, 'env access' by example config patterns, and 'network' by API call examples. No malicious code detected.

Files scanned

1,666

Lines analyzed

findings

Total audits

Low Risk Issues (4)

references/tools-and-resources.md:18 references/tools-and-resources.md:275 references/tools-and-resources.md:312 references/widgets.md:86 references/widgets.md:359

Documentation Examples with Environment Variables

Reference files contain example code showing environment variable access patterns (process.env). These are educational examples teaching proper configuration, not actual credential access.

references/tools-and-resources.md:283

Documentation Examples with Network Requests

Reference files contain example code showing fetch() calls to external APIs. These are educational examples demonstrating API integration patterns.

evals/README.md:9-16 SKILL.md:33-62 references/design-and-architecture.md:7-177

Markdown Code Block Triggers Command Detection

Documentation files use backtick code fences which trigger static scanner 'external commands' detection. These are markdown documentation, not executable code.

SKILL.md:41 evals/implementation.json:4 references/tools-and-resources.md:24-28

Zod describe() Method Triggers Crypto Alert

Code examples using Zod schema .describe() method trigger 'weak cryptographic algorithm' alerts (scanner matches 'des'). These are schema field descriptions, not crypto operations.

Risk Factors

⚙️ External commands (7)

evals/README.md:9-16 SKILL.md:33-62 references/design-and-architecture.md:7-177 references/resource-templates.md:7-139 references/response-helpers.md:5-296 references/tools-and-resources.md:3-314 references/widgets.md:7-449

Audited by: claude

Quality Score

Architecture

100

Maintainability

Content

Community

Security

Spec Compliance

What You Can Build

Creating New MCP Server

Bootstrap a new MCP server project with tools, resources, and prompts

Adding Tools and Resources

Define server-side logic with tool(), resource(), and prompt() methods

Building Interactive Widgets

Create React components with widgetMetadata for visual user interfaces

Try These Prompts

Bootstrap New Server

Create a new MCP server called 'my-server' with a tool that fetches user data by ID. Include proper error handling.

Add Resource Endpoint

Add a resource to my MCP server that returns configuration data from a config://settings URI.

Create Widget Tool

Create a weather display widget that shows current conditions. The tool should accept city name and display temperature, conditions, and humidity.

Design Server Architecture

I need to build an MCP server for a task management app. Analyze what should be tools vs widgets vs resources. List the specific tools, resources, and prompts needed.

Best Practices

Always add .describe() to Zod schema fields for clear parameter documentation
Use widgets when visual or interactive output improves user experience
Reference design-and-architecture.md before jumping to code implementation

Avoid

Jumping to code without reading design-and-architecture.md first
Using tools for everything when widgets would provide better UX
Skipping .describe() on schema fields, making parameters unclear

Frequently Asked Questions

Is this skill still supported?

No, this skill is deprecated. Use mcp-app-builder instead for new MCP server development.

What is the difference between tools and widgets?

Tools perform backend actions and return data. Widgets are React components that provide visual or interactive output. Use tools for data operations and widgets when visual representation improves UX.

How do I handle errors in MCP tools?

Use the error() response helper to return error messages. Check for missing required data and return errors before processing.

Can I use environment variables in my MCP server?

Yes, access configuration via process.env in your tool/resource callbacks. Create .env.example to document required variables.

What response helpers are available?

text(), object(), markdown(), html(), image(), audio(), binary(), error(), mix(), and widget() for different output formats.

How do I test my MCP server?

Run your server locally with server.listen() and test tools/resources using a Claude or Codex client connected to your server.