ga4_referrer_breakdown

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

No annotations are provided, so the description must carry the behavioral burden. It discloses that direct traffic is excluded, which is a key behavioral trait. However, it does not mention authentication requirements, rate limits, data freshness, or any side effects. The behavior is minimally transparent but lacks depth.

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 exceptionally concise: one line for purpose followed by a clean bullet list of parameters. Every sentence serves a purpose, and the structure front-loads the answer. No fluff or redundancy.

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 presence of an output schema and a moderate number of parameters (4 optional), the description is minimal but covers the basics. It does not explain what sessionSource means or how the exclusion of direct traffic is calculated. For a data retrieval tool, this is adequate but not thorough, considering the many siblings.

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?

With 0% schema description coverage, the description adds significant value by explaining all four parameters: date format (YYYY-MM-DD), default values (28 days ago for start_date, today for end_date, 30 for limit), and the purpose of country and limit. This compensates well for the empty schema, though it could clarify that country defaults to no filter.

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 that the tool returns 'Top referrers (sessionSource) excluding direct.' This is a specific verb-resource combination that distinguishes it from sibling tools like ga4_channel_breakdown or ga4_top_pages. The phrase 'excluding direct' adds precision.

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 provides no explicit guidance on when to use this tool versus alternatives. Among many GA4 sibling tools (e.g., ga4_channel_breakdown, ga4_top_pages), there is no mention of context, prerequisites, or when not to use it. The user must infer usage from the name and summary.

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