retention_report

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, and the description still adds real behavioral context: incomplete cohort cells are null, the cohort definition is fixed to first observation, and identities/acquisition history affect accuracy. It omits pagination/volume expectations but the output schema covers return shape.

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 compact sentences with no filler: report definition first, then the accuracy/null caveat, then parameter interaction. Every sentence carries information an agent needs.

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 read-only report with an output schema, the description supplies the cohort definition, the fixed 0..12 week horizon, null handling, accuracy caveats, and window semantics. The main gap is the absence of any routing guidance relative to the many sibling report tools.

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 0% schema description coverage, the description must carry parameter meaning, and it does: event_name's limited scope (returning activity, not cohort definition), and the mutual-exclusion rule between date_from/date_to and days. It leaves the date string format and the days default semantics only implicitly defined, so it is strong but not exhaustive.

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 names the specific artifact produced: weekly first-observed visitor cohorts over weeks 0..12, which an agent can identify as a retention/cohort report distinct from funnel_report or breakdown by subject matter. It lacks an explicit action verb and makes no direct sibling comparison, so it stops short of 5.

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?

It clarifies parameter interaction (event_name restricts returning activity only; date_from/date_to together vs days alone), which is genuinely useful usage context. However, it gives no guidance on when to choose retention_report over sibling reports like funnel_report or compare, so selection guidance is only implied.

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