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

No annotations are provided, so the description carries the burden. It clearly states the inputs and outputs (cost per day, month, and year), which is transparent behavior. However, it does not disclose any edge cases, assumptions (like constant usage), currency defaults, or error handling, which could be relevant for interpreting results. The description adds context but is not exhaustive.

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?

The description is a single, well-structured sentence that front-loads the tool's name and then clearly explains what it does. Every part is relevant, with no filler or repetition. It is immediately understandable and appropriately sized for a simple calculator.

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 simple 3-parameter calculator with no output schema, the description covers the essential information: inputs, what they represent, and the output granularity (day/month/year). It does not explain the underlying formula, but that is not necessary for typical use. Minor gaps like currency or assumptions prevent a 5, but it is largely complete.

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 0%, so the description must compensate. It does so by naming the parameters ('watts, hours per day, and your kWh rate') and connecting them to the output. This adds meaning beyond the raw schema, helping the agent understand that 'rate' is a per-kWh price and 'hoursPerDay' is daily usage. It could be more explicit about units or rounding, but it is sufficient for correct invocation.

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 clearly states the tool's purpose: to calculate the running cost of an appliance based on watts, hours per day, and kWh rate. It uses a specific verb ('work out', 'see the cost') and identifies the resource ('any appliance'). It is distinct from sibling calculators like ev_charging_cost_calculator by focusing on general appliance cost.

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 implies clear usage context: anyone wanting to know an appliance's daily, monthly, or yearly cost from basic inputs. It does not explicitly mention alternatives or exclusions, but the use case is so specific and self-contained that alternative selection is unlikely to be confusing. No explicit 'when not to use' is given, but it is not necessary for this straightforward calculator.

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