Agent ↔ user interface

MCP Apps

The official MCP extension that lets MCP servers return interactive HTML interfaces that render inside the host's chat.

Status
Stable extension, spec 2026-01-26
Governance
Model Context Protocol project (Agentic AI Foundation, Linux Foundation)
Sources
Project siteSpecification
Latest release (checked daily)
2.0.3 on 2026-09-25 · npm @modelcontextprotocol/ext-apps · all releases

What to know

  • Tools declare a UI resource that the host renders in a sandboxed iframe, isolated from the host page and cookies.
  • The app can call tools on its MCP server and ask the host to act through the user's connected capabilities, with user consent.
  • MCP-UI, the community project it grew from, has been standardized into MCP Apps; the MCP-UI packages now implement the MCP Apps spec.
  • The reference SDK is published as @modelcontextprotocol/ext-apps.

When to use it

Use it when your MCP server's results are better used than read, such as dashboards, forms or editors, and you want them to show up inside Claude, ChatGPT or other MCP hosts.

Related standards

MCP · Model Context ProtocolA2A · Agent2Agent ProtocolSKILL.md · Agent SkillsAGENTS.md · AGENTS.mdACP · Agent Client ProtocolPAP · Personal Agent ProtocolAG-UI · Agent User Interaction Protocol (AG-UI)A2UI · A2UITAP · Trusted Agent ProtocolPACT · Personal Agent Consent & Trust Protocol (PACT)ANP · Agent Network ProtocolOASF · Open Agentic Schema FrameworkWebMCP · WebMCPllms.txt · llms.txtAgent Spec · Open Agent Specification

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Reviewed Oct 7, 2026. Spotted something out of date? Email hello@agentatlas.dev.