Get Active Visitor Count

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds valuable behavioral context: it is point-in-time, takes no date/filter/pagination, returns data[0].visitors, and has a polling rate limit. These details go beyond the annotations and help the agent understand operational constraints.

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 model of efficiency: a single sentence stating the core purpose, a quick disambiguation of scope, explicit alternative routing, return format, a polling constraint, and an auth note. Every sentence earns its place, and the most important information (point-in-time nature) is front-loaded.

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 simple tool with 2 parameters and an output schema, the description covers all necessary operational details: what it does, what it does not do (no history/filters/pagination), when to use alternatives, the return shape, rate limiting, and authentication. Nothing an agent needs to call it correctly is missing.

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 100% for both parameters, so baseline is 3. The description adds meaningful context: it explains that domain and websiteId are alternatives, that websiteId is required with a workspace token unless domain is given, and that websiteId is ignored with a website key (though the schema already covers the latter). This clarification helps the agent choose correctly, justifying a 4.

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 clearly states the verb 'Count' and the resource 'visitors active on the site within the last 5 minutes', and immediately distinguishes it from siblings by noting it is point-in-time with no history. It names get_timeseries and get_realtime_map as alternatives, making the tool's unique purpose unambiguous.

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?

Explicitly tells when to use alternatives: 'Use get_timeseries with interval hour for recent trends and get_realtime_map when you need where those visitors are.' Also gives a polling limit ('Poll no more than once every 5 seconds') and states the authentication requirement ('Requires websiteId or domain with a workspace token'). This leaves no ambiguity about when or how to invoke the tool.

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