Get active visitors

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond annotations: the 5-minute window, the realtime-only scope, and the exact return JSON shape, which is especially valuable given there is no output schema.

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 compact and front-loaded. It opens with the core purpose, immediately gives the exclusion for umami_get_stats, then provides structured args, returns, and an example. No sentence is wasted.

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?

Given one optional parameter, a fully descriptive schema, and no output schema, the description supplies the missing return shape and a concrete example. It also routes the agent to the correct sibling for period-based traffic, making the tool easy to invoke correctly without further research.

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 description mirrors the schema's 'Website ID, name, or domain' guidance. It adds a useful example mapping 'example.com' to the website parameter, but most semantic weight is already carried by the schema, so the baseline of 3 is appropriate.

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 states a specific verb and resource: 'Get the number of unique visitors active on a website in the last 5 minutes.' It clearly differentiates itself from umami_get_stats by explicitly labeling itself 'the realtime counter only.'

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 explicitly says when to use this tool versus the alternative: 'This is the realtime counter only. For traffic over a period use umami_get_stats.' The example query further reinforces the intended use case.

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