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

With no annotations, the description carries the full behavioral burden. It discloses key traits: credit cost per call, the conceptual scaling-law nature, ITER-like defaults, and a concrete list of outputs including 3D models, DXF, and a component list. It does not mention permissions or side effects, but for a computational design tool this is a strong disclosure.

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 front-loaded with the main purpose and is dense with relevant details. It is somewhat run-on—one long sentence plus two fragments—but every clause contributes useful information for selection and invocation.

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 the complex design domain, absence of annotations, and no output schema, the description does a good job of covering what the tool computes, what artifacts it returns, and its cost and limitations. It lacks specifics about return formats or error behavior, but an agent has enough to decide and invoke it correctly.

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%, so the description must compensate. It lists ten parameter names with units (e.g., major_radius_m, toroidal_field_T, density_1e20_m3) inside the nested 'params' object, adding substantial meaning beyond the bare schema. It stops short of explaining ranges or defaults for each parameter, so a 5 is not given.

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 states a specific verb and resource: 'Scope a tokamak fusion reactor concept' with detailed params and outputs. It is immediately clear what the tool does, but it does not explicitly distinguish itself from sibling CAD tools such as cad_build or cad_calc, so the top score of 5 is not warranted.

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?

Usage is implied by the phrases 'Concept-level, scaling-law based' and 'Defaults approximate ITER', which signal this is for early-stage conceptual design. However, the description never says when to use this tool versus alternatives, nor does it provide explicit when-not conditions.

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