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

Annotations already establish readOnlyHint=true, so the description's main addition is the 5-minute freshness window and the page/path fields it returns. That is useful context that goes beyond the annotations, though it does not discuss list shape, counts, or any operational quirks.

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?

One compact sentence with no filler; the defining temporal constraint is front-loaded and every word adds meaning.

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 one-parameter, read-only tool, the description covers what is returned (active visitors with page/path) and the relevant time window. It does not detail the site parameter or return format, but no output schema exists and the tool's complexity is low, so the remaining gaps are minor.

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?

The sole required parameter, site, has no schema description, and the description only refers to 'the site' in passing. At 0% schema coverage, the description needed to define the parameter but does not, leaving the agent to infer that site is a site identifier.

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 identifies the resource (visitors) and a unique temporal scope (active in the last 5 minutes), plus the fields (current page and path), which distinguishes it from tools like get_visitors and get_stats. It is phrased as a noun phrase rather than an explicit verb, but the title 'Get Realtime Visitors' supplies the action, so the purpose is 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?

The 'last 5 minutes' phrasing implies this is the realtime/current-visitors option rather than a historical tool, but it never names get_visitors or get_timeseries as alternatives or states when not to use it. The guidance is limited to inferred context.

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