add_circle

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

The annotations already tell the agent this is non-destructive and non-idempotent (each call adds a new element), but the description adds nothing beyond that: no statement of coordinate convention (center vs. corner), units, how elements are layered or selected, or what happens on repeated calls. With 14 parameters and rich style options, a single sentence leaves the mutation behavior largely opaque.

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 definition is a single front-loaded sentence with no filler, which is structurally clean. However, at this brevity it is under-specified rather than genuinely concise for a 14-parameter drawing tool.

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?

An output schema exists, so return-value explanation is not required. Still, for a creation tool with 14 parameters and zero schema documentation, the definition omits essentials such as coordinate semantics, units, and how frame_id or styling interacts with the scene, leaving the agent to guess.

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 description coverage is 0% across 14 parameters, so the description carries the full burden and provides none of it. The meaning of x, y, size (radius or diameter?), frame_id, opacity, roughness, fillStyle, and font_* is entirely undocumented, and the text does not even hint at the required geometry inputs.

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 names a specific verb and resource: "Add a circle (ellipse) to the scene", and the ellipse parenthetical clarifies the shape geometry. It is clearly distinguishable in purpose, but it does not differentiate itself from the many adjacent add_* siblings (add_rectangle, add_diamond, add_arrow), which is what keeps it from a 5.

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?

There is no guidance on when to choose add_circle over add_rectangle or add_diamond, no prerequisites, and no mention of whether the scene must be loaded/selected first. Usage is only implied by the verb.

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