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

Annotations declare it non-read-only, destructive and idempotent; the description backs this up and goes further, disclosing that it is off until enabled, that counting is UTC daily and written every few minutes, that a year is retained (7 days free / all premium), and that switching off permanently deletes what was counted. This is behavioral context well beyond the annotations and fully consistent with them.

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?

It is one dense run-on paragraph of clauses and semicolons with no separation between return content, retention, and the destructive enable/disable behavior. Every clause is informative, but the lack of structure makes it harder to scan than it needs to be.

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 carries the full burden of describing returns, and it does so by enumerating the metrics returned. Combined with retention, default-on state, and enable/disable semantics, an agent has everything needed to call and interpret this tool correctly.

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%, so the baseline is 3, but the description adds real meaning: 'days' defaults to the tier maximum, and 'enable' should only be set when the user has asked. That is meaningful guidance layered on top of what the schema already documents.

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 names a specific resource (visitor analytics for a lambda) and enumerates exactly what is reported: visitors, pages, requests per day, referrers, countries, devices, browsers, OS and crawlers. It is clearly a distinct concern from read_logs or read_lambda, though it never names a sibling to route against, which holds it just below a 5.

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?

It gives an explicit use case ('answer what the user asks about their visitors, or to see which pages matter before changing them') and a conditional rule for the write path ('enable: true switches it on, only when the user asks'). No when-not or named alternative is offered, so it stops short of a 5.

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