diff --git a/crates/mcp/src/tools.rs b/crates/mcp/src/tools.rs
index 79ef49458..7714da5a3 100644
--- a/crates/mcp/src/tools.rs
+++ b/crates/mcp/src/tools.rs
@@ -147,7 +147,7 @@ pub fn tool_definitions() -> Vec<Value> {
                     "type": {"type": "string", "enum": ["frame", "rectangle", "ellipse", "polygon", "star", "line", "arrow", "text", "vector", "section", "component", "slice"], "description": "Layer type"},
                     "x": num("Left, relative to the parent frame (default 0)"),
                     "y": num("Top, relative to the parent frame (default 0)"),
-                    "width": num("Width (default 100; text hugs its content unless width is set, which makes it wrap)"),
+                    "width": num("Width (default 100; text hugs its content unless width is set, which makes it wrap; for a vector with path, width/height scale the path, one alone keeping its proportion, and without them the path's own box is used)"),
                     "height": num("Height (default 100; ignored for lines/arrows and auto-height text)"),
                     "parent": id_schema("Parent frame/group/component id (default: the current page)"),
                     "index": int("Z-index among the parent's children (default: on top)"),
diff --git a/docs/mcp.md b/docs/mcp.md
index 6191b7410..c5ffe99f5 100644
--- a/docs/mcp.md
+++ b/docs/mcp.md
@@ -429,8 +429,8 @@ on; `key` resolves keys the way the canvas does. Commands behind keys:
 `vector.create {path | points}` makes the layer's box from the geometry; `width`/`height` scale
 the geometry to the size asked for (with both, each side independently; with one, the other keeps
 its proportion). A path or point set that draws nothing is refused instead of making an invisible
-0×0 layer, as is a size on an axis the geometry has none of and a size that would collapse both
-axes.
+0×0 layer, as is a size on an axis the geometry has none of (except 0, such as a horizontal line's
+height) and a size of 0 or less on an axis it has, which would flatten it.
 
 Vector edit mode is driven with `run_command` (or `pointer`/`key` for gestures):
 `vector.edit.begin {id? | ids?}` (default the selection; converts shapes to vectors; several layers