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

Annotations already declare readOnly/non-destructive/openWorld=false, so the safety profile is covered. The description adds a genuinely useful behavioral caveat the annotations don't carry: data begins on the Clarity signup date with no prior history, which prevents the agent from promising historical comparisons. Return values are covered by the output schema.

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?

Front-loaded with the resource and metric list, then usage framing, then limits — a sensible order. It is a long single paragraph and the '[DEMO SINTÉTICA]' prefix is non-informative noise, but otherwise every sentence contributes.

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 single-param read-only summary tool with an output schema and full annotations, the description covers what is measured, what questions it answers, what it excludes, and the data-availability constraint. Nothing material an agent needs 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?

Only one parameter, and the schema description already documents date_range with formats and a default (100% coverage). The description adds no additional date-range semantics, so the schema does the heavy lifting — baseline 3 applies.

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?

States a specific resource (Microsoft Clarity visitor behavior/friction) and enumerates the exact metrics returned: scroll depth, active time, rage clicks, dead clicks, quickbacks, excessive scroll, error clicks, JS errors. It also explicitly carves out what it is not ('No mide volumen de tráfico'), which separates it from get_analytics_summary.

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 CRO/UX question patterns ('por qué no convierte', 'dónde se frustran') that tell the agent when to pick this tool, plus an explicit exclusion for traffic-volume queries. It never names the sibling that does handle volume (e.g. get_analytics_summary), so routing is implied rather than explicit.

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