ga4_list_custom_metrics

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

No annotations are provided, so the description carries full burden. It only states a simple listing action. It does not mention pagination behavior (pageSize, pageToken exist in schema), whether it returns all metrics by default, or any side effects (though listing is typically read-only). The presence of pageSize and pageToken implies pagination but the description does not disclose this or any limits.

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 one clear, front-loaded sentence with no filler. It states the action and resource efficiently.

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?

Given the tool has 3 parameters, one required, and no output schema, the description is minimal. It does not explain pagination parameters, the meaning of results, or how this relates to other GA4 tools. For a simple list tool this might be minimally viable, but the pagination parameters and low schema coverage create a gap.

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 only 33% because only propertyId has a description, while pageSize and pageToken lack descriptions. The tool description adds no parameter details. The schema gives basic type info (number with min/max, string), but pageSize and pageToken are not explained. The description does not compensate for the low coverage.

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 description 'Lists custom metrics defined for a GA4 property' uses a specific verb+resource and gives the scope (GA4 property). However, it does not explicitly differentiate from sibling tools like ga4_list_custom_dimensions, though the phrase 'custom metrics' does distinguish it from other GA4 list tools.

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 implies usage context: use when you need to list custom metrics for a GA4 property. However, it provides no explicit guidance on when not to use it or mention of alternatives such as ga4_list_custom_dimensions. The schema requires propertyId, which implies the user needs a GA4 property ID, but this is not stated in the description.

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