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

The annotations already establish that this is a read-only, open-world, non-destructive query. The description adds useful behavior beyond that by explaining the default output shape (one row per event_name with eventCount and totalUsers), optional pagePath slicing, and filtering to an event family. It does not cover authentication, quota, sampling, or error behavior, but the annotations and output schema lower the burden.

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 front-loads the purpose and default output, then explains optional parameters with compact examples. There is no filler, and the line breaks make it easy to scan.

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 GA4 event query with an output schema and full parameter descriptions, the description covers the key selection and invocation details: scope, default aggregation, page slicing, and event filtering. The main missing piece is explicit sibling routing or when-not-to-use guidance.

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, but the description adds practical meaning for group_by_page and event_name_filter beyond the schema text. The homepage scroll-depth example clarifies how group_by_page is useful, and the filter description clarifies focusing on a single event family, though days, limit, and property_id are left to the schema.

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 states a specific verb and resource: an event-level breakdown over the last N days, with concrete event use cases such as scroll depth, outbound clicks, file downloads, and custom events. It is clearly about GA4 event data, but it does not explicitly distinguish itself from siblings like ga4_engagement, ga4_top_pages, or ga4_overview.

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?

It gives clear usage contexts, including scroll depth, outbound clicks, downloads, and custom events, and explains when to use group_by_page and event_name_filter. However, it does not state when not to use the tool or name sibling alternatives for page-level or engagement summaries.

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