Size one duct

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description still adds real value by disclosing output content — recommended diameter, velocity, friction, and the ok/undersized/oversized grade — which is not available elsewhere since there is no output schema.

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 tightly written sentences with no filler. The primary recommend behavior is front-loaded, and the optional grading capability follows immediately.

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?

With no output schema, the description carries the burden of explaining what comes back, and it does so (diameter, velocity, friction, grade verdict). Defaults for role and airflowType live in the schema, so nothing critical is missing, though the sizing standard/basis is left unstated.

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 100%, so all four parameters are already documented in the schema, including the role and airflowType enums and the existing-section shapes. The description adds the grading vocabulary (ok/undersized/oversized) but no syntax or format detail beyond the schema, so the baseline 3 applies.

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 (recommend/grade) and resource (one duct run) with clear scope. The phrase 'one duct run' implicitly contrasts with the sibling size_duct_network, but the sibling is never named, so an agent must infer the boundary.

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 signals two modes of use: recommend a size from CFM, or grade an existing section via the 'existing' input. This implies when the grading path applies, but there is no explicit when-not guidance or named alternative (e.g., use size_duct_network for a whole system).

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