Live User Count

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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds real-time/live snapshot semantics, which is useful context about data freshness, but it does not disclose details like response format or whether the count can change between calls. The annotations make this a moderate rather than severe 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?

The description is a single sentence, front-loaded with the core operation and result, with no filler or repeated information. Every word contributes value.

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-only tool with full schema coverage and annotations, the description is nearly complete: it names the return value (number of live users) and the resource (a site). It could optionally specify the exact response shape, but the low complexity and explicit 'number' wording reduce the need.

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%; the siteId parameter is already described as 'numeric ID or domain identifier'. The tool description adds no additional parameter-level meaning beyond what the schema already provides.

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?

Description uses the specific verb 'Get' and the resource 'current number of live/active users on a site', clearly stating the value returned and its real-time nature. This distinguishes it from siblings like rybbit_list_users and rybbit_get_user, which are about user entities rather than a live site-level count.

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?

'Current' and 'in real-time' imply this is for point-in-time live counts, but there is no explicit guidance on when to choose it over alternatives such as historical metrics or session-based counts. The usage context is implied rather than directly stated.

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