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

Annotations already declare readOnlyHint=true, so the agent knows this is a safe read operation. The description adds the paid-plan restriction and the date-range scoping, which are useful behavioral constraints. It does not disclose return format, pagination, or aggregation behavior, but with annotations covering the safety profile, a 3 is appropriate.

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 that front-loads the resource ('visitor analytics') and includes the key qualifiers (ISO date range, paid plans). It is concise and free of filler, though it could arguably add a bit more context without becoming bloated.

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 analytics tool with three required parameters and no output schema, the description is adequate but minimal. It tells the agent what the tool does and the paid-plan constraint, but it does not describe the response shape, whether data is aggregated, or any limits on the date range. Given the tool's simplicity, this is a passable but not rich definition.

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 67%, with 'from' and 'to' documented as ISO dates and examples, while 'siteId' has no description. The description adds the context that the date range is ISO and that analytics are for a site, but it does not compensate for the undocumented siteId parameter. Baseline 3 is appropriate because the schema does most of the work.

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 ('get') and resource ('visitor analytics for a site') and adds a date-range qualifier, which distinguishes it from sibling tools like get_site_files or list_sites. It does not explicitly name a sibling alternative, but the scope is clear enough to identify what it does.

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 implies usage context: it is for retrieving visitor analytics over an ISO date range, and the '(paid plans)' note gives a prerequisite. However, it does not explicitly say when to use this tool versus alternatives, nor does it mention any exclusions or conditions beyond the paid-plan requirement.

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