MCP Apps
Quick Take
- In brief: MCP Apps links an MCP tool to an interactive interface.
- Useful for: Forms, charts, maps, or design views that need user interaction.
- Main limit: Client support and sandbox behavior can vary.
Overview
A tool may return data that is easier to use in a chart or form than in plain text. MCP Apps lets a host render a related interface alongside the tool result.
Core Definition
MCP Apps is an MCP extension that links interactive UI resources to server tools for a client host to render.
Background and Evolution
MCP Apps extends the tool-and-resource model of MCP with a way to present interactive content. The 2026-01-26 specification is marked Stable; individual hosts still need to implement it.
How It Works
The server declares a UI resource associated with a tool. The host fetches and renders it in a sandboxed frame, then brokers permitted communication between the view and the tool.
Applications in Software Development and Testing
A test tool could show a table of failing checks with filters and links to logs. Test rendering, tool messages, sandbox rules, and error states in each supported host.
Strengths and Limitations
An interactive view can make structured tool results easier to explore. The host decides what it supports and grants; UI content and tool results still need validation.
Comparison with Similar Terms
A regular MCP tool returns data or performs an action. MCP Apps adds an interface for interacting with related results. MCP Elicitation asks the user for input.
Best Practices
Pass only the data the view needs, keep permission boundaries in the host, and test message origins, content security rules, and error handling.
Common Pitfalls
Do not assume every MCP client can render Apps or that the sandbox makes untrusted interface content harmless.
FAQ
Does MCP Apps run its interface directly inside the model?
No. The client host renders the interface and controls its interaction with tools.