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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the bar is lower. The description adds the meaningful detail that the result is a 'simple annualised rate' derived from start/end headcount, but it does not state the exact formula, which headcount figure is the denominator, or how period_months drives annualisation.

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?

A single tightly packed sentence with the core operation front-loaded and zero filler. Nothing in it is redundant or padded.

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 should say more about what is returned (percentage? two figures, raw and annualised?) and the formula basis. It covers inputs reasonably but leaves the agent guessing at the return value and the role of period_months.

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 only 25% (only 'separations' is documented), so the description must compensate. It does convey that headcount is taken at start and end and that the result is scoped to a period, but it never explains period_months, its 1–12 bounds, or the 1-month default that governs the annualisation.

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 description states a specific verb ('Calculates') plus a precise resource ('employee attrition or customer churn rate') and names the inputs it consumes. It is clearly distinguishable from siblings like growth_rate or period_change, though it does not call out any sibling explicitly.

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 input requirements (separations plus start/end headcount); there is no statement of when to prefer this over growth_rate or period_change, and no prerequisites or exclusions. Adequate but leaves routing to inference.

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