sketch_ellipse

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare a non-destructive, non-idempotent mutation in a closed world, so the safety profile is covered. The description adds that geometry is placed into the active sketch, but says nothing about what happens if no sketch is open, whether repeated calls stack duplicate ellipses, or what the result contains.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences with zero filler; the action and its unit-bearing inputs come first and the rotation convention follows. Every clause carries information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Output schema exists so return values need no explanation, and annotations cover the mutation profile. Units and rotation convention are stated; the only real gap is the unstated default origin for the optional center parameters.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is only 40%, leaving center_x_mm, center_y_mm and rotation_deg undocumented in the schema. The description compensates for rotation_deg by defining its convention (counterclockwise from sketch X axis) but does not explain that center defaults to the sketch origin or what coordinate frame centers use.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (draws) and resource (ellipse) plus the context ('in the open sketch') and the defining inputs (two diameters). An agent can distinguish it from sketch_circle/sketch_rectangle by the geometry named, though no sibling is explicitly referenced.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'In the open sketch' implies the prerequisite of an active sketch session, but nothing states that start_sketch must precede it or which alternative sketch primitives to prefer for other shapes. Usage is only implied, not directed.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.