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 goes further, disclosing the actual formula, the rounding-up behavior, and that two counts (low and high end of the coverage range) come back — real behavioral value beyond the structured fields.

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 and output shape are front-loaded in the first sentence, with the formula and reference table following. The data-sheet table is long but earns its place as the default coverage source; only the parenthetical '(scaled for other bag sizes)' feels slightly compressed against the rest.

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, so the description carries the return-value burden — and it does, naming both the conservative and best-case counts. With annotations covering safety, the formula and default coverage data supplied, and all parameters documented in the schema, an agent has everything needed to call this correctly.

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 schema already explains all five parameters and their defaults. The description still adds meaning by tying area, allowance, and coverage-per-bag into an explicit formula and by explaining that the data-sheet coverage scales with bag size — context the enum and numeric fields alone do not convey.

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 concrete verb-and-resource pair (bags of thin-set mortar to buy for a given tile area and trowel notch) along with the two output modes (conservative vs. best-case). It does not, however, distinguish itself from the nearby calc_mortar or calc_grout siblings, leaving the agent to infer the boundary.

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 only implied by the domain wording; there is no explicit 'use this when…' or 'use calc_mortar instead for…' routing. Given that calc_mortar and calc_grout sit in the same sibling list, a one-clause differentiation would have been cheap and valuable.

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