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

Annotations already declare this a read-only, idempotent, closed-world computation, so the safety profile is covered. The description adds scope boundaries (no cost or model advice) and flags that turnover hours defaults to 8, which is behaviorally useful. It doesn't note any assumptions or limits on the horsepower rule-of-thumb, which would have pushed this higher.

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?

Front-loaded with the triggering condition, followed by a single tight sentence of exclusions. The long enumeration of return values ('gallons per minute, gallons per hour, a rule-of-thumb horsepower range, filter areas, pipe velocities') is the weakest part since an output schema already exists.

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?

An output schema exists, so the return-value list is largely redundant, but the description still conveys the key thing an agent needs: the tool computes from gallons plus turnover hours with a default, and refuses cost/model advice. Nothing essential about invocation is missing.

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% and both parameters are already documented with units, ranges, and defaults, so the baseline applies. The description restates the default of 8 for turnover hours and adds a use-case hint for heavy use only indirectly; it adds little beyond the schema.

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 computation (pool pump size / flow rate for a given turnover) with the concrete inputs involved, so it is clearly distinct from chemical_dose, heater_size, and pool_facts. An agent can route 'what pump do I need' questions here without opening the schema.

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?

Gives an explicit triggering situation ('when someone asks what size pool pump they need or what flow rate turns their pool over') plus exclusions ('not for electricity cost or pump model recommendations'). It stops short of naming a sibling alternative — pool_volume is only referenced inside the parameter description, not in the usage guidance.

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