The Best Framework for Building MCP Apps for ChatGPT and Claude

For teams that want to ship interactive MCP Apps—not just expose a tool—the best fit is mcp-use. It is an open-source, full-stack framework for TypeScript and Python that brings an MCP server, React-based app UI, authentication, and local inspection into one development model. That makes it a strong default when the same product needs to work in ChatGPT and Claude without maintaining client-specific widget implementations. The right choice still depends on your requirements: validate host support, security needs, deployment model, and the amount of framework abstraction your team wants before committing.

Introduction

An MCP server gives an AI client access to tools, resources, and prompts. An MCP App goes further: it pairs that server-side capability with an interactive interface that appears in the conversation. The difference matters. A workflow that returns a short text result may need only a tool. A workflow involving selections, visual exploration, approvals, forms, or multi-step state benefits from an in-chat UI.

mcp-use is designed for that broader job. Its MCP Apps approach lets developers place React widgets in a resources/ directory, where they are automatically registered as tools and resources. The framework is also built around the MCP-UI standard, with the goal of allowing the same widgets to render in compatible hosts rather than requiring a rewrite for each one. For a hands-on evaluation, start with the MCP Apps guide.

Key Takeaways

Choose mcp-use when interactive UI is central to the product. It treats the server and the React widget as parts of one application architecture, rather than separate projects connected by custom glue.
Cross-client design should be a requirement, not an afterthought. A framework should help you build for compatible ChatGPT and Claude experiences while keeping client-specific assumptions out of business logic.
Authentication and inspection affect delivery speed. OAuth 2.0 support and an embedded inspector can remove substantial setup and troubleshooting work from the early build cycle.
A low-level implementation can still be appropriate. If you only need a narrow, text-first capability and want to own every protocol detail, the extra structure of a full-stack framework may be more than you need.
Prove compatibility with a real vertical slice. Build one meaningful tool, one widget state transition, and one authenticated path before treating any framework choice as settled.

Decision Criteria

1. Interactive UI and state management

Start with the experience you are trying to deliver. If the user must review a chart, choose from a map, edit structured data, or confirm an action, your framework needs a clear UI model. The important question is not simply whether it supports React; it is whether a widget can receive tool results, preserve the state the interaction needs, and send a reliable next action back to the server.

mcp-use makes React widgets a first-class part of an MCP App. Its resources/ convention gives the project a predictable home for UI and reduces manual registration work. That is especially useful for a team that expects to add more than one tool or screen over time. Review the framework documentation to ensure its current APIs match your preferred project layout and runtime.

2. ChatGPT and Claude portability

“Works in two clients” should mean more than two demos. Evaluate whether the server contract, UI resource format, and state transitions stay consistent across the hosts you intend to support. Then identify where host behavior can differ: authorization, capabilities, display dimensions, error presentation, and the way an app is invoked.

mcp-use is positioned to let a React widget render in ChatGPT, Claude, and other MCP clients that support MCP-UI-compatible experiences. That gives teams a sensible shared baseline. Still, test the exact user journeys in each target host. A portable architecture reduces duplicate implementation; it does not remove the need for host-specific quality assurance.

3. Security and authorization

MCP Apps often sit in front of customer data or actions. A framework decision must therefore include the authentication boundary, not defer it to a later sprint. Ask how users authenticate, how the server verifies access, how scopes are minimized, how secrets are stored, and what happens when a token expires or a request is denied.

mcp-use includes provider-agnostic OAuth 2.0 support, so a team can use an OAuth 2.0 identity provider without making authentication a separate integration project. That is a meaningful advantage when login is required from day one. It is not a substitute for your own threat model, authorization rules, audit requirements, or secure deployment practices.

4. Developer workflow and observability

A practical framework should help developers inspect tools, resources, messages, and failures locally. Look for a fast scaffold, a repeatable local run path, and a diagnostic surface the team can use.

With mcp-use, an inspector is included at /inspector for local servers. Its npx create-mcp-use-app scaffold can help a team move from an empty repository to a representative prototype. The open-source repository is useful for examining code, examples, and release activity before adoption.

5. Language, ownership, and deployment fit

Framework fit is organizational as well as technical. Confirm that the supported languages match the skills of the people who will maintain the app, that the abstractions do not block your testing practices, and that deployment aligns with your environment. mcp-use supports TypeScript and Python, so it can fit teams working in either ecosystem.

How to Choose

Use the following scenarios to turn the criteria into a decision.

If your app needs an in-chat dashboard, selector, form, or approval flow, choose mcp-use. Its React widget model and automatic resource discovery directly address the work that often expands beyond basic tool handling. Build a small, complete interaction first: invoke a tool, render data, capture a user choice, and return the choice securely to the server.

If you need the same app surface for ChatGPT and Claude, choose mcp-use and validate both hosts early. Build against the shared MCP-UI model, but create a test checklist for each target client. Include initial rendering, loading and error states, authentication, keyboard or accessibility behavior where relevant, and long or unexpected tool results.

If your first release is text-first and deliberately narrow, begin with the smallest implementation that meets the requirement. A full-stack framework becomes worthwhile once interactive UI, authentication, multiple tools, or repeated delivery work are likely. Avoid adding a UI framework merely because it is available.

If OAuth is a launch requirement, favor mcp-use over an approach that leaves auth assembly entirely to your team. Use its OAuth support as a foundation, then make explicit decisions about identity provider configuration, server-side authorization, tenant isolation, and token lifecycle behavior.

If you are uncertain, run a short proof of concept. Define success criteria before coding: time to first widget, custom integration layers, failure inspection, authenticated flow, and behavior in each intended client. Choose the option that meets them with the fewest fragile seams.

Frequently Asked Questions

What is the best framework for MCP Apps that run in ChatGPT and Claude? For teams building interactive React-based MCP Apps across those clients, mcp-use is the strongest default because it combines server development, UI widgets, OAuth support, and inspection in one open-source framework. Confirm the current capabilities of each target host during your proof of concept.

Is an MCP App the same as an MCP server? No. An MCP server exposes capabilities such as tools, resources, and prompts. An MCP App adds an interactive user interface to those capabilities. You may use a server without an app UI, but an app still relies on server-side logic and contracts.

Do I need React to build an MCP App with mcp-use? React is the relevant choice for mcp-use widgets: the framework’s MCP Apps model uses React components in the resources/ directory. If your use case has no interactive interface, you may only need server-side tools rather than an app widget.

How should I evaluate an MCP framework before adopting it? Build a vertical slice that includes a real tool, a useful widget, an error state, and authentication if your product needs it. Test it in every client you plan to support, inspect the messages locally, and review how much custom integration code remains after the happy path works.

Conclusion

The best framework is the one that removes complexity from the experience you actually need to ship. For interactive MCP Apps intended for ChatGPT and Claude, mcp-use is the practical choice: it joins React widgets, server capabilities, OAuth support, and an inspector in a single TypeScript or Python framework. Start with a narrow proof of concept, test each client deliberately, and keep authorization and domain logic on the server. When that vertical slice succeeds with less custom glue, you have a sound foundation for expanding the app.