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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuine behavioral substance beyond that: the exact computation chain (coverage → gallons per coat → total with loss → kits) plus the derived wet-mils output, which tells the agent what the tool actually returns despite no output schema.

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 answer to 'what does this give me,' then a compact formula block. It is dense but every formula shown maps to an output or intermediate the agent needs; only the trailing wet-mils note feels slightly tacked on.

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 a fully documented 6-parameter schema, no output schema, and read-only annotations, the description covers what is needed to call it correctly. The only real gap is that it never explicitly names the return fields or units of the result (gallons, kit count), though the formulas make them inferable.

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% with defaults on all six parameters, so the baseline is 3. The description earns an extra point by tying parameters into the formula (solids by volume, dry mils, area, coats, loss) and implicitly confirming that wet mils is derived rather than an input, which helps the agent map real-world data-sheet values to the right fields.

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 verb+resource ('How much epoxy floor coating to buy') and enumerates exactly what is produced: coverage per gallon, gallons per coat, total with losses, and kits. This clearly separates it from neighbors like calc_paint, calc_thinset, and calc_flooring_tile, which cover different materials.

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 formula and by the parameter hints ('from the data sheet' for solids and dry mils), so an agent can infer the inputs come from a product technical data sheet. But there is no explicit when-to-use/when-not statement and no naming of alternatives such as calc_paint for non-epoxy coatings.

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