Event Names

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

Annotations already fully describe the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the description's additive burden is low. It does add the useful scope qualifier 'custom event names' and the 'occurrence counts' output concept. However, it does not disclose default date-window behavior when no dates are supplied or whether built-in events are excluded, leaving some residual behavioral uncertainty.

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?

Two sentences with the core purpose front-loaded in the first: verb, resource, and output in a single clause. The second sentence, 'Useful for discovering what events are being tracked,' is slightly redundant with the first since retrieving event names inherently enables discovery, but it is short and adds a mild use-case signal. No fluff or repetition of schema content.

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 list tool with strong annotations and a fully documented 7-parameter schema, the essentials are present: what it returns, at what scope, and how parameters work. Gaps remain: there is no output schema and the description only sketches the return shape without format detail, and in a 40+ sibling namespace with four event-related neighbors, the absence of routing guidance is a real completeness shortfall.

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 the schema itself is unusually rich: siteId explains the accepted formats, filters enumerates all filter dimensions and provides a concrete example array, and timeZone and pastMinutes params include defaults and examples. The description adds no parameter-level detail, but at full coverage the baseline 3 applies — the schema fully carries this burden.

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 uses a specific verb ('Get') with a clear resource ('all custom event names') and specifies the return payload ('occurrence counts') scoped to a site, which unambiguously conveys the core function. It does not, however, explicitly differentiate itself from the event-related siblings (rybbit_list_events, rybbit_get_event_properties, rybbit_get_event_timeseries), which occupy a crowded namespace — the qualifier 'custom event names' only partially disambiguates.

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 phrase 'Useful for discovering what events are being tracked' gives an implied discovery use case, which is real guidance but not explicit. It provides no when-not-to-use conditions and names no alternatives, which is a notable gap given the presence of four adjacent event-focused siblings (list_events, get_event_properties, get_event_timeseries, get_user_event_breakdown) that an agent could plausibly confuse.

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