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

Annotations already declare readOnlyHint, idempotentHint, and closed-world behavior. The description adds useful context by specifying output units and the Gulf climate setting for the UAE and Saudi, though it does not elaborate on calculation assumptions or edge cases.

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, front-loaded sentence that efficiently conveys the tool's core function, supported inputs, output units, and a regional feature. The appended web page URL is minimal and useful.

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 fully explains the return values (BTU/h, tons, kW). It also summarizes the inputs and highlights the Gulf climate specialization, making it complete enough for an agent to invoke 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 all parameter details are already in the schema. The description names a few key inputs (area, ceiling height, sun, occupants) but adds no syntax, constraints, or defaults beyond what the schema provides.

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 states a specific verb ('Size') and resource ('air conditioner or heater'), names the output units (BTU/h, tons, kW), and lists key inputs. It clearly distinguishes this tool from generic area or unit converters by focusing on HVAC sizing.

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 purpose implies usage for sizing air conditioners or heaters, but there are no explicit when-to-use or when-not-to-use guidelines. Alternative sibling tools like area_calculator or electricity_cost_calculator are not mentioned, leaving routing to inference.

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