A script never runs

Confirm the script is attached to the correct object, simulation is running, and the browser console has no initialization error. Scene-wide scripts must be assigned in Scene Settings.

Collision callbacks never fire

Call gameObject.registerForCollisions() inside init(). For trigger callbacks, also enable Trigger Volume on the sensor object.

An animation is not found

Print gameObject.getAnimationNames() and copy the exact case-sensitive clip name. Confirm the mesh actually contains animation tracks.

A vehicle ignores input

Apply non-zero driver input through the vehicle API. The engine activates sleeping chassis bodies when driver input arrives; confirm the object is a configured vehicle rather than a generic rigid body.

An MCP tool cannot find a project or scene

Call accounts_list first, use the returned account ID, then list projects and scenes within that same account. Scene IDs are UUIDs; project and account IDs use prefixed IDs.

MCP physics says the editor is unavailable

Open the exact project and scene in a visible editor tab, keep the tab active, and try physics_run_simulation again.