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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds only that the report targets the user's own site — nothing about GA4 quota/rate limits, sampling, or latency for large queries, which would be genuinely useful for a live external API.

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?

A single sentence with a front-loaded verb, a colon-delimited operand list, and one worked example. No filler, and the highest-value information (what it does, what it accepts) comes first.

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 9 fully-documented optional parameters and annotations carrying the safety profile, the description needs to establish scope and it does. The absence of return-shape detail is acceptable since no output schema exists, though nothing explains what a result row looks like.

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 100%, so the baseline is 3. The description's example filter ('sessionSource==instagram') and date phrasing ('over the last 28 days') are illustrative rather than additive syntax the schema lacks; the filter operator grammar lives in the schema, not the description.

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+resource ('Run a Google Analytics 4 report') scoped to 'your own site', and enumerates the operands (dimensions, metrics, date range, filters). An agent can distinguish it from ga4_realtime_report and ga4_list_properties without opening the schema.

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 embedded example ('sessions and conversions from Instagram by landing page over the last 28 days') gives concrete when-to-use context, and the schema note routes property discovery to ga4_list_properties. However, it never says when to prefer ga4_realtime_report or states any exclusion.

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