Attempting to run the compiled Dart tooling MCP Server in the @modelcontextprotocol/inspector fails

[domesticmouse]

Steps to reproduce:

1. Get the dependencies

$ dart pub get
Resolving dependencies...
Downloading packages...
  _fe_analyzer_shared 80.0.0 (82.0.0 available)
  analyzer 7.3.0 (7.4.4 available)
  coverage 1.12.0 (1.13.0 available)
! dart_mcp 0.2.0-wip from path ../dart_mcp (overridden)
  dtd 2.5.0 (2.5.1 available)
  lints 5.1.1 (6.0.0 available)
  unified_analytics 7.0.2 (8.0.1 available)
  web_socket 0.1.6 (1.0.0 available)
  web_socket_channel 3.0.2 (3.0.3 available)
Got dependencies!
8 packages have newer versions incompatible with dependency constraints.
Try `dart pub outdated` for more information.

2. Compile lib/main.dart to an executable

$ dart compile exe bin/main.dart
Generated: /Users/brett/Documents/GitHub/ai-dart/pkgs/dart_tooling_mcp_server/bin/main.exe

3. Run the inspector

$ npx @modelcontextprotocol/inspector
Starting MCP inspector...
⚙️ Proxy server listening on port 6277
New SSE connection
Query parameters: [Object: null prototype] {
  transportType: 'stdio',
  command: 'npx',
  args: '-y @modelcontextprotocol/server-filesystem /Users/brett/Documents/GitHub/colorist_ui',
  env: '{"HOME":"/Users/brett","LOGNAME":"brett","PATH":"/Users/brett/.npm/_npx/5a9d879542beca3a/node_modules/.bin:/Users/brett/Documents/GitHub/developer_assistant_mcp/node_modules/.bin:/Users/brett/Documents/GitHub/node_modules/.bin:/Users/brett/Documents/node_modules/.bin:/Users/brett/node_modules/.bin:/Users/node_modules/.bin:/node_modules/.bin:/opt/homebrew/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin:/Users/brett/.local/bin:/Users/brett/.cargo/bin:/Users/brett/flutter/bin:/Users/brett/.pub-cache/bin:/Users/brett/Library/Application Support/JetBrains/Toolbox/scripts:/Users/brett/bin:/Users/brett/flutter/bin:/Users/brett/.pub-cache/bin:/Users/brett/Library/Application Support/JetBrains/Toolbox/scripts:/Users/brett/bin","SHELL":"/bin/zsh","TERM":"xterm-256color","USER":"brett"}'
}
Stdio transport: command=/opt/homebrew/bin/npx, args=-y,@modelcontextprotocol/server-filesystem,/Users/brett/Documents/GitHub/colorist_ui
Spawned stdio transport
Connected MCP client to backing server transport
Created web app transport
Created web app transport
Set up MCP proxy
🔍 MCP Inspector is up and running at http://127.0.0.1:6274 🚀

4. In the web app, configure the path to the executable, and select the List Tools button.

For debugging context, here is my flutter doctor output:

[✓] Flutter (Channel stable, 3.29.3, on macOS 15.4.1 24E263 darwin-arm64, locale en-AU) [406ms]
    • Flutter version 3.29.3 on channel stable at /Users/brett/flutter
    • Upstream repository https://github.com/flutter/flutter
    • Framework revision ea121f8859 (3 weeks ago), 2025-04-11 19:10:07 +0000
    • Engine revision cf56914b32
    • Dart version 3.7.2
    • DevTools version 2.42.3

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0) [3.0s]
    • Android SDK at /Users/brett/Library/Android/sdk
    • Platform android-35, build-tools 35.0.0
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
      This is the JDK bundled with the latest Android Studio installation on this machine.
      To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
    • Java version OpenJDK Runtime Environment (build 21.0.3+-79915917-b509.11)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 16.3) [1,028ms]
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 16E140
    • CocoaPods version 1.16.2

[✓] Chrome - develop for the web [70ms]
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2024.2) [70ms]
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 21.0.3+-79915917-b509.11)

[✓] IntelliJ IDEA Community Edition (version 2024.3.1.1) [69ms]
    • IntelliJ at /Users/brett/Applications/IntelliJ IDEA Community Edition.app
    • Flutter plugin version 83.0.4
    • Dart plugin version 243.23177

[✓] VS Code (version 1.99.3) [9ms]
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.108.0

[✓] Connected device (4 available) [5.7s]
    • Brett’s iPad (wireless) (mobile) • 00008103-001169D42223001E • ios            • iOS 18.4.1 22E252
    • macOS (desktop)                  • macos                     • darwin-arm64   • macOS 15.4.1 24E263 darwin-arm64
    • Mac Designed for iPad (desktop)  • mac-designed-for-ipad     • darwin         • macOS 15.4.1 24E263 darwin-arm64
    • Chrome (web)                     • chrome                    • web-javascript • Google Chrome 135.0.7049.115
    ! Error: Browsing on the local area network for Brett’s iPhone. Ensure the device is unlocked and attached with a cable or
      associated with the same local area network as this Mac.
      The device must be opted into Developer Mode to connect wirelessly. (code -27)

[✓] Network resources [509ms]
    • All expected network resources are available.

• No issues found!

[jakemac53]

Let me take a look, this definitely worked in the past but we also recently updated to the new spec

[jakemac53]

I confirmed this still works fine for me, I am using v0.10.2 of the inspector fwiw. Any additional information you can provide?

I see that there is a failed post request error in your screenshot which makes me thing the inspector itself is having issues, we don't make any requests.

[domesticmouse]

Feel free to re-assign to me, I'll look at this next week. I'm crunching for a presentation tomorrow night. =)