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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds real value beyond that: it discloses the output content (pounds and bags), the included high-salt dilution guidance and retest cautions, and explicitly that no equipment control occurs.

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?

Three compact sentences, front-loaded with the core computation before the caveats. Every sentence carries information; nothing is padded.

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 usefully states what is returned (pounds, bags, dilution guidance, retest cautions). It is close to complete for this calculator, the only gap being the undocumented bag-size and bag-price inputs.

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 0% for 5 parameters, so the description must compensate. It names the key inputs (gallons implied by 'swimming pool', salt ppm, target) and the pounds/bags output, but says nothing about bagSizeLb or bagPriceUsd, leaving two numeric parameters wholly undocumented.

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?

Specific verb ('Estimate') and resource ('swimming pool salt addition in pounds and bags'), with the inputs that drive it (measured salt ppm, user-supplied target). It is clearly distinct from the sibling calculate_pool_volume, which computes a different quantity.

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?

Usage is implied by the phrase 'measured salt ppm and a user-supplied target', and 'No equipment control' sets a boundary. But there is no explicit when-to-use/when-not guidance or any reference to the sibling tool.

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