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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the per-mode behavior (what each check inspects) but says nothing about auth needs, rate limits, or cost. Adequate but thin given annotations do most of the work.

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 front-loaded with the mode selection and then walks each mode compactly in parallel structure. It is telegraphic but every clause carries routing or input information; nothing is padding.

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?

Modes, their purposes, and their required inputs are covered, and an output schema exists so return values need not be explained. Minor gaps are the undocumented detail/memory_key semantics, but those are covered by the schema descriptions.

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 baseline is 3, but the description adds value the schema cannot express: with zero top-level required params, it clarifies the conditional requirement of url for ga4/consent modes and the required gsc/ga4 array shapes for gsc_vs_ga4. Only detail and memory_key go unmentioned, and those are self-documenting in the schema.

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 lead sentence is a bit abstract ('whether the numbers add up'), but the mode breakdown gives concrete, specific checks: GA4 tags/events/duplicates, cookie banner and Consent Mode v2, and GSC clicks vs GA4 sessions. An agent can tell what each mode does without opening the schema. It does not differentiate itself from adjacent siblings like technical or measure, which keeps it out of 5 territory.

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 explicitly instructs 'Pick with mode' and maps each mode to its purpose and required inputs, which is real routing guidance among the tool's own modes. However, it never states when to choose this tool over siblings such as technical, measure, or scan_page, so the alternative-selection guidance is incomplete.

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