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 without the description. The description adds domain context (GA4 API naming, relative date forms) but says nothing about pagination, cost, rate limits, or result shape. No contradiction with annotations.

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, purpose front-loaded, then the two syntax rules that most often cause a failed call. No filler, though the second sentence packs two distinct rules without visual separation.

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 6-parameter, 2-required reporting tool with no output schema, the description covers the high-risk parameters (dates, dimension/metric naming) but leaves the return structure, row-limit behavior, and dimension/metric compatibility rules unaddressed. Adequate for a basic call, incomplete for confident use.

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 only 33%, so the description must compensate. It supplies the naming convention for dimensions and metrics with concrete examples ('sessionDefaultChannelGroup', 'sessions') and the accepted date formats for start_date/end_date ('YYYY-MM-DD', '28daysAgo', 'today'), which are undocumented in the schema. Only limit is left unexplained, and its schema bounds/default are largely self-explanatory.

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 ('Run a GA4 report') that an agent can distinguish from ads_report, gsc_query, and meta_insights by the GA4 qualifier. It does not explicitly name a sibling or scope its difference, so it stops short of 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?

The GA4 domain and the API-name convention imply when this tool is the right one versus ads_report or gsc_query, but there is no explicit when-to-use, prerequisite, or exclusion guidance. Usage must be inferred from the name and the example values.

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