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

Beyond the read-only, idempotent, and non-destructive annotations, the description discloses that prices and omitted costs are not looked up and that private projects or purchases are not accessed. It also usefully lists the returned results, formula, assumptions, method version, and source-page URL, though it does not describe error behavior or infeasible break-even inputs.

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, and the four short sentences are easy to scan. The generic "tested BusCalc worksheet" wording adds little, but the remaining output and data-access disclosures earn their place.

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?

Together with the detailed nested input schema and annotations, the description is sufficient for an ordinary break-even calculation, and its return-value list partly offsets the absence of an output schema. Remaining gaps include the unexplained optional units object and behavior when price does not exceed variable cost, but these do not prevent normal 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?

With schema description coverage at 33%, the description needs to compensate, but it only mentions fixed costs and does not identify the required price and variable-cost inputs or explain the optional top-level units object. The nested schema documents fixed, price, and variable well, so parameter meaning is not wholly absent, but the description itself adds little.

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?

The opening sentence gives a specific operation and outputs: finding the units and revenue needed to cover fixed costs. This clearly identifies break-even sales and distinguishes it by subject matter from the sibling calculators, though it does not explicitly contrast it with nearby tools such as buscalc_decision_feasibility.

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?

"Use this tested BusCalc worksheet when the task matches its inputs and scope" provides a basic when-to-use cue. However, it is largely circular and gives no concrete prerequisites, exclusions, or alternative sibling tool for related but different tasks.

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