modelcontextprotocol / modelcontextprotocol/ext-apps

Documentation for MCP Apps does not match 2026-07-28 specification

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Description

The specification and documents still refers to "initialize"

It does not describe out how to add the ui extension in the client request for capabilities _meta structure per client call for the 2026-07-28 specification

https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx

{
"method": "initialize",
"params": {
"protocolVersion": "2024-11-05",
"capabilities": {
"extensions": {
"io.modelcontextprotocol/ui": {
"mimeTypes": ["text/html;profile=mcp-app"]`

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First steps

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  3. Fork the repository and make your change on a branch.
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Research direction

Start with specification/2026-01-26/apps.mdx and compare its initialize example with the 2026-07-28 specification. Check how the client request describes the UI extension and the capabilities _meta structure for each call. Done means the specification and documentation use the current terminology and show the required request structure.

Written by the indexing model from the issue text.

Assessment

Domain
documentation
Issue type
Documentation
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Active
Clarity
Mostly clear
Newbie friendliness
68/100

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