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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's job is behavioral detail. It adds real value by disclosing the annualization behavior and summarizing the computed outputs, though it doesn't state assumptions or edge cases (e.g. zero starting headcount) for a calculation tool.

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 sentences, each earning its place: what it computes first, then when to use, then which siblings to prefer. Front-loaded and free of padding.

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 an output schema present, return values needn't be explained in depth, and the description still summarizes them. Full schema coverage, explicit alternatives, and documented annualization make the definition complete for a four-parameter calculator.

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% and each parameter already documents its meaning and bounds, so the baseline is 3. The description names the inputs but adds no format or interpretation detail beyond what the schema provides.

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 and resource ('Calculate the employee turnover (attrition) rate') plus the scope (month/quarter/year) and the exact inputs used. It also differentiates itself from two named siblings, so an agent can pick it without opening a schema.

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?

Gives an explicit when-to-use ('when you have headcounts and separations and need the rate') and names two concrete alternatives with the conditions that select them: employee_retention_rate for split leaver data, employee_turnover_cost for dollar costing.

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