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

Annotations already declare readOnly, non-destructive and closed-world, so the safety profile is covered. The description adds substance beyond that: which behavioural metrics are computed and the explicit non-inclusion of conversions, which prevents a common misread of 'quality by source'.

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?

Two tight sentences: metric scope first, then use cases, then the exclusion. The '[DEMO SINTÉTICA]' marker is noise but negligible against otherwise zero-waste phrasing.

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 annotations, a full output schema and a fully documented single parameter, the description covers everything needed to call it correctly. The only residual gap is that it does not clarify when to prefer this over the similarly named traffic-source and clarity page tools.

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?

There is a single optional parameter and the schema documents it fully with formats and a stated default of the last 30 days. The description adds nothing about the date range, so the baseline of 3 for high schema coverage 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 and dimension (friction by acquisition channel, source/medium) plus the exact metric set returned: sessions, scroll, active time, rage/dead click rates and quickbacks. Naming Clarity and those metrics distinguishes it from the generic sibling list_analytics_traffic_sources.

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 three concrete question phrasings that map to when this tool applies (paid traffic frustration, fast-bouncing channels, traffic quality by source) and explicitly excludes conversions. It does not name which sibling to use instead for conversion or page-level questions, so routing is implied rather than prescribed.

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