Measure a product's funnel

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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces 'Read-only' while adding real behavioral context: only mature/resolved cohorts are counted, null is returned with reliability 'insufficient' when the sample is too small, and results include sample size and a reliability flag. That is meaningful disclosure beyond the annotations.

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?

Front-loaded with the core action and scope, followed by usage guidance and return behavior; every sentence carries information. It runs slightly long, but nothing is redundant 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, the description need not enumerate return fields, and it still covers usage, cohort maturity, small-sample handling, and read-only status. Nothing an agent needs to call this correctly is missing.

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 baseline is 3, but the description adds conceptual meaning to the parameters by explaining that only cohorts 'old enough to have resolved' are counted, which clarifies the role of maturity_days and the window parameters beyond the raw ISO-date documentation.

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 (measure) and resource (call-centre approval, post-office buyout, and return rates for one product) with explicit scope (date window, resolved cohorts only). An agent can distinguish this from the sibling tools without opening any 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 clear when-to-use guidance: 'before any decision that depends on approval or buyout rates, instead of assuming the portfolio-wide 65% approval and 52.5% buyout.' It does not name a sibling alternative, but the triggering condition is unambiguous.

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