timeline.inspect returns a feature's definition in the shape timeline.edit's set takes, so agents no longer guess field names: timeline.edit had no documented format ({"extent": {"distance": …}} worked, but only by trying). The new read-only command (feature: id or name) returns type, definition (the editable fields and their current values; bookkeeping and large payloads such as sketch geometry and imported STEP text are left out and listed under omitted), inputs (label, parameter name, expression, unit) and the feature's error and warning. timeline.edit's params doc points to it, and the book's Solid features chapter documents the edit format with the fields of the common features. Tests: inspect, edit by the field names it shows, inspect again (extrude, fillet, sketch); no undo step; hostile feature arguments are refused

docs/mcp.md

@@ -62,6 +62,11 @@ Claude Desktop (`claude_desktop_config.json`), bridged to a running app:
 | `open` | `path` | Open a `.solvecraft` design, a STEP file (`.step`/`.stp`) as a new design holding its bodies (an Import base feature), or a 3MF/STL file as mesh bodies. |
 | `save` | `path?` | Save the design (to its current file without `path`). |
 
+To change a feature after it is made, read its definition with `execute` `timeline.inspect`
+(`{feature}`: id or name) and change fields with `timeline.edit` (`{feature, set}`; e.g.
+`{"extent": {"distance": "30"}}`). The fields per feature type are listed in the book's
+*Solid features* chapter.
+
 Resources: `solvecraft://design` (inspect JSON with measurements) and `solvecraft://commands`
 (the catalog).