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

Annotations already declare readOnlyHint=true, destructiveHint=false and closed-world, so the safety profile is covered structurally. The description adds the computational formula, but says nothing extra about error handling (non-zero time is only in the schema) or return shape, so it is a modest contribution beyond annotations.

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 compact clauses: the formula first, then the sibling disambiguation. Zero filler and the core definition is front-loaded.

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 a fully described two-parameter schema, an output schema present, and safety annotations, the only thing needed is what the tool computes and how it differs from lookalikes. The formula and the two named exclusions satisfy that; only broader sibling differentiation is missing.

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 100% with both parameters documented including the 'non-zero' constraint on time. The description's formula implicitly maps work and time to the output, which is mild added meaning, but it introduces no syntax or edge-case semantics beyond the schema. Baseline 3 is appropriate.

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 gives the exact formula 'P = W / t' with unit Watts, so the operation and its inputs are unambiguous. It also names two siblings it is not (math x^y and the unit power converter), though it leaves ambiguity against other power-related siblings like calculator_ee_power and calculator_electrical_power.

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 phrase 'Distinct from math x^y and unit power converter' provides useful negative routing, telling the agent when NOT to pick this tool. But there is no explicit positive condition stating when to prefer this over calculator_physics_work or the other electrical power tools, leaving selection partly inferential.

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