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

Adds substantial context beyond the readOnly/idempotent annotations: an account-plan precondition that can cause failure, the implicit default range and timezone, the caveat that filtered reports exclude imported historical aggregates, and the note that visitor identity is privacy-safe and rotates daily. These are non-obvious data-scope and error traits an agent could not infer from structured fields.

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?

Four sentences, all load-bearing, opening with the resource and scope before defaults, preconditions, and data caveats. No restatement of the title or name.

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?

With no output schema, the description usefully enumerates the report dimensions returned, and it covers default range, plan requirement, and data exclusions. It leaves out return shape/aggregation details (e.g. how trend series are bucketed, whether results are paginated or capped), which matters for a multi-dimension analytics call.

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 67%, and the description compensates by supplying the 30-day default and UTC default that the schema does not state, plus concrete usage for filters.path. It does not explain the semantics of the remaining exact-match filters (e.g. country needing a two-letter code, which the schema does cover) or how multiple filters combine.

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?

Specific verb + resource ('Read ... analytics for the connected blog') plus an enumeration of exactly what is retrievable: traffic totals, previous-period comparisons, hourly/daily trends, top pages, sources, channels, devices, locations, interactions. This distinguishes it cleanly from the real-time sibling get_current_visitors and from content-listing siblings.

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?

Gives concrete selection guidance within the tool ('Use filters.path for a single post or page') and states the default scope (30 days UTC) and the eligibility precondition (requires an eligible API plan). It stops short of naming an alternative tool or an explicit when-not-to-use condition, so it is clear context without full routing.

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