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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so "Changes nothing" largely restates the safety profile; openWorld (live GA data) is never surfaced in prose. The "highest first" ordering hint is genuine behavioral context, but it is also covered by the order_by schema description, so added value is modest.

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?

Three sentences, front-loaded with the core capability and sort behavior, followed by compact reference lists. The dimension/metric enumerations are the longest part but are directly actionable, so 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?

Covers what the tool does, valid field vocabulary, and the no-mutation guarantee for a 9-parameter tool, but with no output schema it never describes the shape of returned rows. The days-vs-start_date/end_date interplay and limit behavior are left entirely to the schema.

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 the baseline is 3, and the description earns an extra point by enumerating common GA4 dimension and metric names — the schema only says "GA4 dimension/metric names" with a regex and provides no enums. This materially reduces the risk of passing invalid field names.

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 verb and resource: run an arbitrary GA4 report from dimension/metric names. "Any GA4 report" signals flexibility versus the preset sibling analytics_landing_pages, though it never names a sibling explicitly, so differentiation is inferred rather than stated.

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 implied: reach for this when you need an arbitrary dimension/metric combination rather than one of the curated report siblings. There is no explicit when-to-use, when-not-to-use, or named alternative to route against analytics_landing_pages or run_gaql.

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