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 beyond that by disclosing the exact deterministic formula and units, so the agent knows precisely how the output is derived and that density must come from the user's plant.

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?

Two tight sentences, output unit front-loaded ahead of the formula. Nothing extraneous; every clause either names the result or defines the computation.

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 explicitly names the return value and unit (tons), and annotations cover safety, so an agent can call this confidently. Only minor edge-case behavior (e.g., zero/invalid inputs) is left implicit.

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, but the formula adds real value: it shows how L, W, depth (in inches, converted /12) and density (lb/cu ft) combine into tons, clarifying parameter roles and unit handling beyond the field labels.

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 ('Tons of hot-mix asphalt') with scope ('driveway or lot') and the exact inputs used. It is trivially distinguishable from sibling calculators like calc_concrete_slab or calc_mulch_gravel by material and unit of output.

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?

The phrase 'for a driveway or lot' implies the domain but gives no explicit when-to-use, when-not-to-use, or alternative selection guidance against the many other calc_* siblings. An agent must infer that this is the right tool for asphalt tonnage versus concrete or gravel.

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