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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behaviour not in the annotations: that `total_rows` reflects the full result size and that paging is done with `offset`. It says nothing about quota limits, invalid metric/dimension error behaviour, or comparison-period output shape.

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 sentences, front-loaded with the operation and its result shape, followed by the pagination caveat. No filler, no repetition of parameter names already in the schema.

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 12 parameters, an output schema and full annotations, the description covers the core call adequately. However, it omits two things an agent would benefit from: that metrics/dimensions must be valid GA4 API names discoverable via ga4_list_dimensions_and_metrics, and that property_id comes from ga4_list_properties (the schema mentions it, the description does not reinforce it).

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 description coverage is 83%, so the schema already documents dates, filters, order_bys and the comparison period in detail. The description only adds one piece of meaning beyond that: `total_rows` is the unpaged result size, which frames the offset parameter. Baseline 3 applies given the rich 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?

Names a specific verb and resource ('Run a Google Analytics 4 report') and spells out the shape of the result (metrics broken down by dimensions over a date range, with filters, sorting and comparison). It does not explicitly contrast itself with ga4_run_realtime_report or ga4_list_dimensions_and_metrics, so sibling differentiation is left implicit through the date-range framing.

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?

Usage is only implied: the date-range language hints this is the historical-report tool rather than the realtime one, and no prerequisites or exclusions are stated. Nothing tells the agent when to prefer this over ga4_run_realtime_report or get_data, and it does not point to ga4_list_dimensions_and_metrics for valid field names.

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