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

Annotations already establish read-only, closed-world behavior, so the description does not need to restate safety. It adds useful behavioral context by naming the DOE formula, clarifying the coldest-month temperature-rise assumption, and noting that warm-up hours exclude losses.

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 primary output is front-loaded, followed by formulas and assumptions. It is dense but technical content is mostly necessary; a few phrases could be tightened, but there is little filler.

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?

There is no output schema, but the description names the key outputs and explains the formulas and assumptions needed to interpret them. It does not specify exact return field names or structure, which keeps it from being fully complete for an agent expecting structured results.

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 100%, so the parameter descriptions already do the baseline work. The tool description adds value by explaining how the parameters relate mathematically, especially temperature rise, rate-factor multiplication, gas input from efficiency, and warm-up time from gallons and output.

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 calculation and resource: heater output in Btu/h for an outdoor pool, plus gas input, matching heat pump size, and warm-up time. It is clearly distinguishable from siblings like calc_pool_volume, calc_pool_turnover, and calc_tankless_water_heater_size.

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 outdoor-pool framing and DOE formula imply the intended use, but the description does not explicitly say when to choose this tool over related pool or heater calculators. No exclusions or alternatives are named.

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