create_ellipse

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

With no annotations, the description carries the full burden. It explains angle conventions (0=top, clockwise) and arcInnerRadius semantics, which is useful. However, it does not disclose return behavior, side effects, or interactions with existing canvas elements, leaving gaps for a creation tool.

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?

The description is well-structured, with the main purpose front-loaded followed by arc parameter details and a concrete recipe. The recipe is useful but slightly verbose, and the decorative line could be trimmed. Overall, it earns its place without excessive bloat.

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?

Given 17 parameters, no output schema, and no annotations, the description is far from complete. It covers only a subset of parameters and lacks information on return values, canvas behavior, or prerequisites. The recipe adds practical value but does not fill the gaps for a tool of this complexity.

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 0%, so the description must compensate for 17 parameters. It only explains arcStartAngle, arcEndAngle, arcInnerRadius, and implicitly width/height. Many parameters like shadow, gradient, fillOpacity, and strokeOpacity remain undefined, which is insufficient given the low schema coverage.

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?

The description clearly states 'Create a circle or ellipse' with a specific note that equal width/height produces a perfect circle. This distinguishes it from sibling tools like create_rectangle and create_line, and the mention of arc/donut support adds further specificity.

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?

The description implies usage for circles/ellipses and provides a detailed recipe for multi-color donut rings, but it does not explicitly state when to use this tool versus alternatives like create_rectangle or when not to use it. The recipe is a concrete example, but no exclusions or alternative comparisons are given.

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