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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safe, self-contained nature of the call is covered. The description adds the computation formula, which usefully signals deterministic pure math, but says nothing about default values being applied when arguments are omitted or about the response shape.

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 sentences, zero filler: the outcome is stated first, then the exact formula. Front-loaded and fully earned.

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 does name the return values (daily and yearly kWh plus cost), which is the key missing piece. It does not mention that all four inputs are optional with defaults, but the schema covers that.

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 watts, rate_per_kwh, days_per_year and hours_per_day. The description references the same four quantities in its formula but adds no units, ranges, or defaults beyond what the schema provides — 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?

States a specific verb+resource: computes daily/yearly kWh and dollar cost to run an appliance. It clearly distinguishes itself from the construction-materials calculators, though it never names or contrasts with nearby siblings like calc_solar_panel or calc_voltage_drop.

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 cost to run any appliance from its wattage, hours of use and your electricity rate,' which tells the agent the inputs needed. There is no explicit when-to-use, when-not-to-use, or alternative-tool guidance.

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