Add initial PoC for MCP Apps for select tools under Insiders by mattdholloway · Pull Request #1957 · github/github-mcp-server · GitHub

Summary

Based on initial work by @tommaso-moro

This PR adds support for MCP Apps, enabling rich interactive UIs for MCP tools.

New MCP App UIs

get_me - User profile display with avatar and stats
issue_write - Create/update issues with title, body, and Markdown editor
create_pull_request - Create PRs with title, body, and draft/regular toggle

Implementation

UI Layer (ui/): React + Primer design system, built to single HTML files via script/build-ui
Server Integration: HTML assets embedded in binary, exposed as MCP resources linked via tool metadata

Insiders Mode

All MCP Apps functionality gated behind Insiders

UI resources and metadata only available when enabled
Generic insidersOnlyMetaKeys mechanism for future experimental features

These new UIs require a new React app that exists under the ui folder with components made available in iframes for clients that support the feature. This has been extensively tested under VSCode-Insiders.

This will require additional support in Remote MCP to ensure Insiders and resources support works correctly.

Why

As part of https://github.com/github/copilot-mcp-core/issues/1125

What changed

Added ui/ directory with React + Primer design system apps for get_me, issue_write, and create_pull_request
Added script/build-ui to compile React apps into single HTML files
Added pkg/github/ui_embed.go to embed built HTML assets into binary
Added pkg/github/ui_resources.go to register UI resources with the MCP server
Added UI metadata (Meta.ui.resourceUri) to get_me, issue_write, and create_pull_request tools
Added CSP configuration for avatar image loading in get_me resource
Added _ui_submitted mechanism to distinguish UI form submissions from LLM tool calls
Added WithInsidersMode() to inventory builder to gate experimental features
Added insidersOnlyMetaKeys mechanism to strip insiders-only metadata when disabled
Updated CI workflows to include UI build step

MCP impact

No tool or API changes
Tool schema or behavior changed
New tool added

Prompts tested (tool changes only)

Security / limits

No security or limits impact
Auth / permissions considered
Data exposure, filtering, or token/size limits considered

Tool renaming

I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
- I have added the new tool aliases in deprecated_tool_aliases.go
I am not renaming tools as part of this PR

Note: if you're renaming tools, you must add the tool aliases. For more information on how to do so, please refer to the official docs.

Lint & tests

Linted locally with ./script/lint
Tested locally with ./script/test

Docs

Not needed
Updated (README / docs / examples)

…ce CreateIssueApp to manage existing issue data

…server into mcp-ui-apps-3

When InsidersMode is enabled, append '(insiders)' to the User-Agent string sent with GitHub API requests, enabling server-side adoption tracking.

Just tested this again, nice improvements! Some things I have noticed

What is the behaviour of these tools on hosts where MCP Apps is not supported? For example, in issue_write and create_pull_request, when Insiders is on and _ui_submitted is false, the tool early-returns a placeholder message like "Ready to create an issue". So it seems like on a host without MCP Apps support, users would get the placeholder text instead of the tool actually executing. I think we should have a way for people opting into insiders but using hosts that won't support Apps (which include 1P ones like Copilot CLI) to still be able to use the tool without the UI
On hover, the "Write" and "Preview" options in the markdown look inconsistent with the rich text options, in that they don't have rounded corners. A quick fix is to round the corners to make them consistent
In the markdown editor, the toolbar isn't responsive: I cannot scroll horizontally to reveal some of the options (like bullet point list, numbered list)

The UI to create a PR doesn't seem to work anymore: when I click "create pull request" it effectively creates the pull request, but it shows the error message instead of the success UI, even though it does create the PR

In the issue creation success screen, we need to add spacing between the issue icon and the title of the issue (same for the PR success UI)

(nit) I have noticed that I cannot just pull up the create issue UI without populating it with title and body to create an issue. It only works by having the model write a test title and body, calling the issue_write tool and then showing the form pre-populated with that mock text for me to edit. Is that intentional? I wonder if we should let folks see an empty UI that they can fill out
(nit) maybe unrelated, but getting 422 error when trying to create a draft PR as it assumes my default branch is main but instead it's master. Don't think this was introduced with these changes but wanted to flag, maybe we can show a more helpful error message here

Screenshot

…nsistent in textarea

Left a comment, but overall LGTM for Insiders!

We could add Goose here too, as it also supports MCP Apps

Overall LGTM for Insiders!

Arshadigital.ir

tommaso-moro and others added 24 commits February 2, 2026 16:54

PoC full flow (hello world example)

67a4793

add avatar resource domain

7d2b463

add postmessage logic and richer UI

7606aec

add create issue ui

02ce9bf

update ui for issue creatioon

d53ff41

fix

e3d5db7

ignore banner

b149642

update docs after rebase

92aabf2

update toolsnap for get_me

8b55d08

new UI changes

06270c7

update docs

a770719

update workflows that need ui build

23de0bc

add UI diff

e2a8582

fix build ui step for windows runners to use git bash

5bb6228

fix UI diff

157ba4d

refactor issue creation UI

c927390

add AvatarWithFallback component and update UserCard to use it; enhan…

6d0eda6

…ce CreateIssueApp to manage existing issue data

fix formatting of button labels

2b0d8cc

add create pull request functionality with UI support and insiders

b8dc0d5

update docs

2d186da

add test for insiders mode handling in ServerTool schema

072f5c4

remove show_ui param for now

adc1053

make insiders mode metadata stripping generic

ee0a440

remove ui diff

2b8f062

mattdholloway added the insiders Features for the Insiders mode of the GitHub MCP Server label Feb 4, 2026

Merge branch 'main' into mcp-ui-apps-3

6070471

github deleted a comment from github-actions Bot Feb 4, 2026

mattdholloway added 2 commits February 4, 2026 13:13

Merge branch 'mcp-ui-apps-3' of https://github.com/github/github-mcp-…

d0f0334

…server into mcp-ui-apps-3

fix CI

37da563

mattdholloway marked this pull request as ready for review February 4, 2026 14:36

mattdholloway and others added 6 commits February 9, 2026 17:07

fix UI spacing

4994f84

Add insiders flag to User-Agent header

c031cd3

When InsidersMode is enabled, append '(insiders)' to the User-Agent string sent with GitHub API requests, enabling server-side adoption tracking.

Merge branch 'main' into mcp-ui-apps-3

97b501f

Merge branch 'main' into mcp-ui-apps-3

64ac427

Merge branch 'main' into mcp-ui-apps-3

ef5bc56

Merge branch 'main' into mcp-ui-apps-3

2b41c03

tommaso-moro reviewed Feb 11, 2026

View reviewed changes

Comment thread ui/src/apps/pr-write/App.tsx

github deleted a comment from FuzzysTodd Feb 11, 2026

mattdholloway and others added 6 commits February 12, 2026 09:29

address ui feedback

8103657

added ui/no-ui support

c08ff04

Merge branch 'main' into mcp-ui-apps-3

e6b175b

improve active state UI for write and preview button. make padding co…

baf3331

…nsistent in textarea

return to prev non ui check

dfbd526

use hardcoded client name check for ui support

6219a58

tommaso-moro previously approved these changes Feb 12, 2026

View reviewed changes

linter fixes

b9d6a7e

mattdholloway dismissed tommaso-moro’s stale review via b9d6a7e February 12, 2026 12:47

Merge branch 'main' into mcp-ui-apps-3

69f4bb5

tommaso-moro previously approved these changes Feb 12, 2026

View reviewed changes

merge fix

ca41f33

mattdholloway dismissed tommaso-moro’s stale review via ca41f33 February 12, 2026 12:53

linter fix 2

ef99178

tommaso-moro approved these changes Feb 12, 2026

View reviewed changes

mattdholloway merged commit e83440d into main Feb 12, 2026
16 checks passed

mattdholloway deleted the mcp-ui-apps-3 branch February 12, 2026 13:03

BrewTestBot mentioned this pull request Feb 19, 2026

github-mcp-server 0.31.0 Homebrew/homebrew-core#268385

Merged

github-actions Bot mentioned this pull request Feb 20, 2026

[ca] CLI Version Updates: Claude Code 2.1.49, Copilot 0.0.412, GitHub MCP Server v0.31.0 github/gh-aw#17117

Closed

Copilot AI mentioned this pull request Feb 20, 2026

chore: bump Claude Code → 2.1.49, Copilot → 0.0.412, GitHub MCP Server → v0.31.0 github/gh-aw#17120

Merged

tommaso-moro mentioned this pull request Feb 23, 2026

Reduce context usage for get_pull_request_review_comments using pull_request_read #2062

Merged

13 tasks

arshadigital reviewed Jun 27, 2026

View reviewed changes

+              // This is a temporary workaround until the Go SDK adds an Extensions field
+              // to ClientCapabilities (see https://github.com/modelcontextprotocol/go-sdk/issues/777).
+              // Once that lands, detection should use capabilities.extensions instead.
+              var uiSupportedClients = map[string]bool{

Add initial PoC for MCP Apps for select tools under Insiders by mattdholloway · Pull Request #1957 · github/github-mcp-server · GitHub

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Add initial PoC for MCP Apps for select tools under Insiders - #1957

Add initial PoC for MCP Apps for select tools under Insiders#1957
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               cmd/github-mcp-server/github-mcp-server
               # VSCode
               .vscode/*

               vendor
               bin/
               # macOS

		@@ -1,5 +1,5 @@
		.idea
		cmd/github-mcp-server/github-mcp-server

Add initial PoC for MCP Apps for select tools under Insiders by mattdholloway · Pull Request #1957 · github/github-mcp-server · GitHub

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Add initial PoC for MCP Apps for select tools under Insiders - #1957

Add initial PoC for MCP Apps for select tools under Insiders#1957mattdholloway merged 74 commits intomaingithub/github-mcp-server:mainfrom mcp-ui-apps-3github/github-mcp-server:mcp-ui-apps-3Copy head branch name to clipboard

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Summary

New MCP App UIs

Implementation

Insiders Mode

Why

What changed

MCP impact

Prompts tested (tool changes only)

Security / limits

Tool renaming

Lint & tests

Docs

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Add initial PoC for MCP Apps for select tools under Insiders#1957
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