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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral context beyond annotations: it exposes the exact formula, unit conversions, and the assumption that trade percent is grams of available chlorine per 100 mL. It omits output rounding/precision, but is transparent for a pure calculator.

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 purpose is front-loaded in the first sentence, followed only by the formula and unit conversions needed to understand the calculation. There is no filler; every sentence contributes to understanding the result.

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-optional-parameter calculator with full schema coverage and read-only annotations, the description supplies the output unit, input relationships, and formula. With no output schema, the first sentence still specifies the returned measure (fluid ounces), leaving no essential gap for correct invocation.

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 baseline is 3. The description adds meaning beyond the schema by showing how the three parameters relate in the formula and by defining strength_pct as trade percent grams of available chlorine per 100 mL, which is not stated in 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 the specific output (fluid ounces of liquid chlorine / sodium hypochlorite) and the goal (raise free chlorine by a target ppm) from named inputs (pool volume, product strength). This clearly distinguishes it from pool salt and pool volume siblings, even without naming them explicitly.

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?

No when-to-use guidance or alternatives are given. The description explains the calculation but never says when to choose this over calc_pool_salt or calc_pool_volume, nor does it state prerequisites, exclusions, or typical scenarios.

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