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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is fully covered. The description's one added behavioral fact is the ~30-minute lookback window, which is genuinely useful. It says nothing about quota/rate-limit behavior, whether property must be numeric vs. 'properties/123', or what metric/dimension names are accepted.

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?

One functional sentence, front-loaded with the verb and resource, plus the data-window qualifier. The trailing 'Tools revision: d80f65c0.' is internal build metadata that carries no value for an agent selecting or calling the tool.

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?

An output schema exists and annotations are rich, so the return and safety story need not be spelled out. However, for a tool whose only required inputs are free-form GA4 metric/dimension name strings with zero schema documentation, the description leaves a significant gap an agent cannot close from structured fields alone.

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 0% across three parameters, so the description must compensate and largely does not. Only 'property' is hinted at ('for a property'); metrics and dimensions are left as bare string arrays with no indication that they must be valid GA4 API names or that realtime only supports a restricted subset of metrics/dimensions — a real source of invocation errors.

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?

It states a specific verb and resource (run a GA4 realtime report) and even scopes the data window to the last ~30 minutes. It does not explicitly contrast with ga4_run_report, ga4_run_pivot_report, ga4_run_cohort_report, or ga4_run_funnel_report, though 'realtime' implicitly separates it from the standard report tool.

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 '(last ~30 min)' parenthetical implies the tool is for near-live monitoring rather than historical analysis, which is useful selection context. There is no explicit when-not guidance, no mention of the alternative report tools, and no stated prerequisites such as needing an existing GA4 property ID.

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