mcp-use MCP Apps Builder Skill

mcp-use/mcp-use publishes mcp-apps-builder, an Agent Skill for building production-ready MCP servers and MCP Apps. It is written as a navigation guide: the skill tells coding agents which reference files to read before implementing tools, resources, prompts, widgets, authentication, deployment, or framework changes.

This is useful for Claude Code, Codex, Cursor, and other coding agents because MCP Apps work is easy to get subtly wrong: tool schemas, resource wiring, widget state, auth, deployment, and client compatibility all affect whether the final server is safe and usable.

Knowledge Freshness

The upstream repository is active and the skill is tied to current mcp-use SDK patterns. MCP Apps, ChatGPT Apps, Claude MCP clients, widget APIs, transport support, OAuth behavior, inspector behavior, and Manufact/mcp-use cloud deployment can change quickly.

Use the skill for workflow structure and mcp-use-specific guardrails, then check the current repository README, docs, SDK package versions, and reference files before generating or modifying production MCP code.

Retrieval Sources

This listing is grounded in:

• The mcp-use/mcp-use repository README.
• The upstream skills/mcp-apps-builder/SKILL.md file.
• Representative reference files for architecture, tool implementation, and widget basics.
• The public skills.sh listing for mcp-apps-builder.
• Current GitHub repository metadata for mcp-use/mcp-use.

Core Workflow

Install the skill from the mcp-use repository:

npx skills add https://github.com/mcp-use/mcp-use --skill mcp-apps-builder

Update installed skills:

npx skills update

Then invoke it before MCP server work:

Use the mcp-use MCP Apps Builder Skill before modifying this MCP server.

The skill's first rule is to determine whether the workspace is already an mcp-use project. If a package imports from mcp-use/server or depends on mcp-use, it tells the agent to modify the existing project rather than scaffold a fresh app.

Capability Scope

The skill covers mcp-use MCP server and MCP Apps development:

Production Rules

Use this skill with MCP-specific change control:

• Read the relevant reference files before editing server.tool(), server.resource(), server.prompt(), widget code, auth middleware, or deployment configuration.
• Keep one tool per capability and give each tool a clear schema, description, and side-effect boundary.
• Validate user input at the tool boundary with Zod or equivalent schema logic.
• Keep widget state owned by the widget and pass only necessary props from tool responses.
• Do not expose secrets, private URLs, OAuth client secrets, cookies, or tokens in generated config, docs, examples, prompts, screenshots, logs, or PR text.
• Test locally with the mcp-use inspector before deployment.
• Treat deployment as a security boundary: review auth, CORS, rate limits, logging, observability, and public tool authority before publishing.

Use Cases

• Ask Codex to scaffold a new mcp-use server without mixing up tools, resources, prompts, and widgets.
• Use Claude Code to add a widget-backed MCP App tool to an existing project.
• Ask Cursor to review an MCP server for schema, validation, auth, and widget state mistakes.
• Use an agent to convert a local prototype into a production-deployable MCP App with inspector testing and deployment notes.
• Guide a code review for unsafe MCP tool surfaces, proxying behavior, auth gaps, or over-broad side effects.

Source Review

• The repository README describes mcp-use as a fullstack MCP framework for building MCP Apps for ChatGPT and Claude, plus MCP servers for AI agents.
• The README links directly to the mcp-apps-builder skill on skills.sh.
• The skills.sh page provides the install command and identifies the repository as mcp-use/mcp-use.
• The SKILL.md file states that agents should read it before creating, modifying, debugging, reviewing, or answering questions about MCP server work.
• The skill routes agents to detailed reference files instead of relying on short examples in the entrypoint.
• The architecture, tools, and widget reference files document production patterns beyond a generic prompt snippet.

Duplicate Review

Checked current content/skills/, content/mcp/, content/agents/, content/tools/, open pull requests, and repository-wide content for mcp-use/mcp-use, mcp-apps-builder, MCP Apps Builder Skill, mcp-use skill, mcp-builder, and openapi-to-mcp. Existing MCP capability-pack skills cover OAuth hardening, Streamable HTTP migration, server authoring security, and other general MCP topics, but no dedicated mcp-use MCP Apps Builder Skill entry, exact source URL duplicate, target file, or open duplicate PR was found.

Disclosure

Editorial listing. No paid placement or affiliate link is used. The skill lives in the mcp-use/mcp-use repository. The repository metadata reports MIT license for mcp-use, while this skill folder includes Apache-2.0 license text; verify the exact license file if redistributing bundled skill artifacts.