Reference and Troubleshooting
A one-page cheat sheet for the whole series. For the exhaustive per-plugin lookup use CrimsonEditorUtilities -> API Reference.
Console commands
| Command | Does |
|---|---|
ModelContextProtocol.StartServer [port] | Starts the HTTP server (optional port override). |
ModelContextProtocol.StopServer | Stops the server. |
ModelContextProtocol.RefreshTools | Rebuilds the tool list after enabling/disabling toolsets. |
ModelContextProtocol.GenerateClientConfig <Client> | Writes a client config: ClaudeCode, Cursor, VSCode, Gemini, Codex, or All. |
Settings at a glance
| Setting | Where | Default |
|---|---|---|
Server Port Number | Editor Preferences -> Model Context Protocol | 8000 |
Server Url Path | Editor Preferences -> Model Context Protocol | /mcp |
Auto Start Server | Editor Preferences -> Model Context Protocol | false |
Enable Tool Search | Editor Preferences -> Model Context Protocol | true |
Enable Crimson MCP | Project Settings -> Crimson -> Crimson MCP | false |
Crimson toolset inventory (examples)
Every Crimson plugin ships a toolset when Crimson MCP is on. A few you will use most - confirm live names with describe_toolset:
| Toolset | From | What it does |
|---|---|---|
CrimsonSourceToolset | CrimsonEditorUtilities | Read files and list directories in the project/engine tree. |
CrimsonPluginToolset | CrimsonEditorUtilities | List plugins, audit the cardinal rule, scaffold a new plugin. |
CrimsonAssetToolset | CrimsonEditorUtilities | Find, inspect, create assets and find gameplay tags. |
CrimsonUIToolset | CrimsonUI | Inspect and mutate the live PIE UI layer stack. |
Troubleshooting
| Symptom | Cause and fix |
|---|---|
| Agent connects but sees no tools. | Server not running, or the registry is empty under tool search. Start the server, then ModelContextProtocol.RefreshTools. |
| My Crimson toolsets never appear. | Enable Crimson MCP is off, or the editor was not restarted after enabling it. Turn it on and restart. |
| A custom toolset never registers (no error). | Editor module registered before the subsystem existed. Set that module's .uplugin to "LoadingPhase": "PostEngineInit". |
| Toggling Enable Crimson MCP does nothing. | It is read once at startup. Restart the editor. |
| A toolset shows but I want it hidden. | Untick it in the MCP toolbar's Toolset Visibility section, or add its name to Blocked Names in Toolset Registry settings. |
| Port 8000 is taken. | ModelContextProtocol.StartServer 8080, then regenerate the client config so it points at the new port. |
Go deeper
The model behind all of this is in CrimsonCommon -> Concept: How Crimson MCP Works. To manage exposure in depth see CrimsonCommon -> How-To: Manage MCP Toolsets. To add your own tools to any plugin see CrimsonCommon -> How-To: Add MCP Tools to a Plugin.