WebEngine MCP Plugins for Coding Agents

WebEngine ships two plugins that turn any compatible coding agent into a browser/device operator: the agent observes the live application through MCP, interacts with it, then generates UI code in your stack (Playwright+TS, Selenium, WebEngine C#).

Plugin Profile Tools Skills
plugins/webengine-web --profile web (Selenium) 29 webengine-web, webengine-scaffold
plugins/webengine-mobile --profile mobile (Appium) 17 webengine-mobile, webengine-scaffold

Both plugins share one server binary (AxaFrance.WebEngine.Mcp, command webengine-mcp) and carry two packaging formats in the same folder: Agent Plugins 1.0 (plugin.json + mcp.json) for VS Code/Copilot, and .codex-plugin/plugin.json + .mcp.json for Codex.

Prerequisites

  • .NET 10 (the dnx launcher ships with the SDK) for the zero-install run below.
  • The package published to NuGet (maintainers: dotnet pack + dotnet nuget push). Before that, use the local-build fallback in each plugin README.
  • A browser (Chrome/Edge/Firefox) for web; an Appium server (default http://localhost:4723) for mobile.

Test the server once (no agent needed):

dnx AxaFrance.WebEngine.Mcp --profile web --transport stdio
# or, after dotnet tool install -g AxaFrance.WebEngine.Mcp:
webengine-mcp --help

GitHub Copilot (VS Code)

Full plugin (skills + server, recommended):

  1. Run Chat: Install Plugin From Source and paste https://github.com/AxaFrance/webengine-dotnet, or register the marketplace AxaFrance/webengine-dotnet in chat.plugins.marketplaces, or point chat.pluginLocations at a local clone's plugins/<name> folder.
  2. Enable the plugin. Its MCP server starts automatically with it.
  3. Verify: MCP: List Servers shows webengine-web/webengine-mobile; Chat: Configure Skills lists the skills.

Manual (no plugin install): copy plugins/<name>/skills/* to .github/skills/ and the mcp.json content into .vscode/mcp.json. This repository's own .vscode/mcp.json is a working example (local build).

Codex (CLI, IDE extension, desktop)

codex plugin marketplace add AxaFrance/webengine-dotnet --sparse .agents/plugins
# then install webengine-web / webengine-mobile from the Plugins Directory

This repository also ships .agents/plugins/marketplace.json for repo-scoped installs. Manual alternative:

codex mcp add webengine-web -- dnx AxaFrance.WebEngine.Mcp --profile web --transport stdio

plus copying plugins/<name>/skills/* to ~/.codex/skills/ (restart Codex). Project-scoped MCP goes in .codex/config.toml (trusted projects); see plugins/<name>/config.toml.snippet.

Claude Code

Copy plugins/<name>/skills/* to .claude/skills/ (project) or ~/.claude/skills/ (personal), and register the server in claude_desktop_config.json:

{ "mcpServers": { "webengine-web": {
  "command": "dnx",
  "args": ["AxaFrance.WebEngine.Mcp", "--profile", "web", "--transport", "stdio"]
} } }

Restart Claude Code and verify the tools list.

OpenCode

Skills: copy plugins/<name>/skills/* to .agents/skills/ (project, also picked up by Codex/Cursor) or ~/.config/opencode/skills/. Server in opencode.json:

{ "$schema": "https://opencode.ai/config.json",
  "mcp": { "webengine-web": { "type": "local",
    "command": ["dnx", "AxaFrance.WebEngine.Mcp", "--profile", "web", "--transport", "stdio"],
    "enabled": true } } }

(OpenCode v2 nests servers under mcp.servers; check your version's docs.)

Cursor

Project skills in .cursor/skills/ (global: ~/.cursor/skills/), server in .cursor/mcp.json using the same stdio command as above.

Troubleshooting

  • No tools / garbled handshake: plain dotnet run prints a launch banner to stdout, which breaks MCP stdio. Use dnx, dotnet tool, a published exe, or dotnet exec <dll>.
  • dnx cannot resolve the package: it is not on NuGet yet — use the local-build fallback from the plugin README.
  • Mobile session fails: start the Appium server first and check appsettings.json (Appium:DefaultServerUrl).
  • Both tool sets collide (StartSession twice): never expose both profiles in one process; use --profile web|mobile.
  • Click intercepted / stale refs: this is page behavior, not an install issue — the skills' references/blockers.md (cookies, modals, SPA re-renders) covers the protocol.