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

With zero annotations, the description carries the full burden and does substantial work: it discloses coarsening to hundreds, that below-threshold cohorts return no number, and a ~20 queries/day rate limit. It does not say whether suppression yields an empty result or an error, which is the one remaining behavioral gap.

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 compact parenthetical packed with decision-relevant facts and no filler. Every clause (coarsening, suppression, rate limit) changes how an agent should call or interpret the result.

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?

For a one-parameter read tool with no output schema, the description covers the privacy behavior, the suppression case, and the rate limit. It leaves the input's provenance and the exact return shape to be inferred.

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 0% with one required parameter, and the description says nothing about cohort_id — not its format, not where to obtain it (presumably from pag_audiences_list). The only structured hint is a regex pattern, which is insufficient on its own.

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 operation and resource: a cohort size estimate. An agent can tell this apart from pag_audiences_list (which lists audiences) without reading the schema. Sibling differentiation is implied but never made explicit.

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 description never says when to prefer this over pag_audiences_list or pag_campaigns_proof, nor whether a cohort_id must come from a prior listing call. Usage is only inferable from the purpose itself.

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