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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is fully covered and the description adds nothing to it. It does contribute that the result includes CO₂ kg alongside cost and points to list_bundles for related 'energie' calculators, but omits assumptions such as the default 0.25 EUR/kWh price and any day/year basis.

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?

Three short sentences, front-loaded with the core action followed by usage and outputs. The inputs/returns list is slightly redundant with the schema and output schema, but it is compact and earns most of its space.

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?

For a deterministic three-parameter calculation with a full output schema, the description supplies purpose, use case, and the extra bundle cross-reference, which is enough to call it correctly. The remaining omission is sibling disambiguation against calculate_electricity_cost.

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 three parameters (power_w, hours_day, price_kwh) are already documented including units and the 24-hour cap. The description restates the inputs ('power W, daily hours, kWh price') without adding format, default, or edge-case meaning, which is the baseline when the schema does the heavy lifting.

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+resource ('Compute annual electricity cost of a household appliance') and scopes it to an annual figure, which is clearer than a generic cost tool. It does not, however, distinguish itself from the close sibling 'calculate_electricity_cost' (nor from calculate_led_savings/laundry_cost), so an agent must guess which one fits.

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 and replacement decisions' gives a usage context but no when-not guidance and no named alternative among the many electricity/cost calculators. Usage is implied rather than explicitly routed, which is the minimum viable level.

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