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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world scope, so safety needs no restating. The description contributes domain framing (audiences used for reports and Google Ads remarketing) and pagination behavior, but the pagination detail is largely duplicated from the schema and nothing is said about auth/scope requirements or behavior on an invalid property id.

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?

Front-loaded with the verb and resource, followed by payload contents and pagination in a compact two-sentence block; nothing is wasted except the field enumeration, which is slightly redundant given the output schema. The trailing "Tools revision" line is metadata rather than description but is negligible.

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 an output schema present and annotations covering safety, the description needs only to establish scope, identifier format and paging — all of which it does. The remaining gap is the lack of a prerequisite note on obtaining the property id, which for a 3-parameter list tool is acceptable.

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 67%, and the uncovered parameter is the required `property` — the description compensates by giving its exact format, properties/<id>. That is real added meaning over the schema. Minor friction: the prose says "next_page_token" while the actual argument is named `page_token`, which could momentarily mislead on the name even though the schema clarifies.

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 ("List the audiences of a GA4 property") and pins it to the canonical resource path form properties/<id>, which distinguishes it from the Google Ads sibling list_audiences and from ga4_create_audience. It even enumerates what an audience record contains, so the agent knows this is a read of audience definitions rather than members.

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 by the resource-scoped phrasing, and the GA4 prefix plus the <id> path form implicitly steer the agent away from the Google Ads list_audiences. However, there is no explicit when-to-use statement, no precondition (e.g. that a property id must first come from ga4_list_properties), and no pointer to ga4_create_audience as the mutation counterpart.

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