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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, so the safety profile is covered structurally. The description adds "Returns yearly savings," but says nothing about assumptions, units of the result, or rounding. With annotations carrying safety, a 3 is appropriate.

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?

Front-loaded with the core action, then usage, inputs, return, and a cross-reference — a logical order with little waste. The input enumeration partly duplicates the schema, keeping it short of a 5.

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 an output schema present, the description needn't detail return values, and it doesn't need to. Combined with full schema coverage and covering annotations, the description supplies what an agent needs to invoke the tool 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 100%, so the schema already documents all five parameters with types and defaults. The description merely re-lists them ("old wattage, LED wattage, daily hours, kWh price, bulbs") without adding format, unit, or default semantics beyond the schema. Baseline 3.

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 (compute) and resource (energy and money saved switching incandescent/halogen to LED), which is far more specific than the dozens of generic calculate_* siblings. An agent can immediately tell this is an LED-retrofit savings calculator rather than a generic electricity-cost tool.

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?

"Use for energy audit" gives an implied context, and "See list_bundles for related 'energie' calculators" points to a discovery path, but there is no explicit when-to-use vs when-not against the closest competing siblings (e.g. calculate_electricity_cost, calculate_solar_roi). Guidance is present but leaves the boundary with alternatives to inference.

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