GA4 dimensions & metrics metadata

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, covering safety. The description adds valuable behavioral context: it returns custom dimensions/metrics, metric types (TYPE_SECONDS, etc.), and deprecated API names. It does not contradict annotations and enriches the agent's understanding of what to expect from the output.

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 a single, dense sentence that front-loads the main purpose (listing dimensions/metrics) and then adds key details (custom ones, types, deprecated names, filtering). Every word earns its place; there is no fluff or repetition. It is concise and well-structured.

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 read-only metadata listing tool with strong annotations (read-only, idempotent) and no output schema, the description is fairly complete. It explains the content (dimensions, metrics, types, deprecated names) and the filtering mechanism. It does not mention pagination or result limits, but these are not critical for such a tool. The description covers the essentials an agent needs to call it correctly.

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% (search and propertyId are described; kind has an enum and default but no description). The description adds a small hint about using search to keep output small, which complements the schema's already-detailed search description. However, it does not explain the 'kind' parameter beyond its enum values, and the schema already covers most semantics. Baseline 3 is appropriate.

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 clearly states the verb ('List') and the resource ('dimensions and metrics available for a GA4 property'), and specifies details like custom ones, metric types, and deprecated API names. It distinguishes itself from siblings like ga_run_report (which runs reports) and ga_list_properties (which lists properties) by focusing on metadata. This is a precise, actionable definition.

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 explains what the tool does but does not explicitly state when to use it versus alternatives. It mentions filtering by search to keep output small, which implies usage for exploration, but there is no direct guidance on when not to use it (e.g., for data retrieval) or naming alternative tools. This leaves the decision to the agent's inference.

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