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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds substantial context beyond them: the data_availability outcome vocabulary (complete, observed_zero, no_rows, partial_collection, access_error) with the explicit warning that no_rows and access_error do not mean zero. It also flags that result strings originate outside the system and must be treated as data, not instructions, plus the per-call token cost.

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 purpose is correctly front-loaded in the first sentence, and most sentences carry real information, but the whole thing is one undifferentiated block mixing auditing, prompt-injection policy, idempotency protocol and billing. Some content is noise or confusing translation artifacts, notably the 'anonymous taste calls' clause and the trailing Korean token note.

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 only 3 parameters, no nested objects, no output schema and permissive read-only annotations, the description covers everything an agent needs: what is inspected, that it is non-mutating, how to decode the result's availability status, and how to handle retries. Nothing material is missing for a correct invocation.

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 property_id and account_link_id are already documented; the description's value-add is the detailed contract for request_idempotency_key (generate before the first request, reuse only for recovery, new key for new execution, distinct from a provider-specific idempotency_key), which the schema defers to it. It adds nothing further about property_id or account_link_id beyond the schema text.

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 (audit) and the exact resource scope (GA4 measurement setup for one property: data streams, key events, property settings), then explicitly separates itself from the write path by noting it is read-only and never changes tags or settings. An agent can distinguish it from google__analytics__measurement__create/update without opening any 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?

Gives an explicit primary use case (find missing or mismatched setup so the customer can fix it) and a second concrete trigger: read back current values when the property settings update tool's outcome is unknown. That is direct routing against the sibling mutation tool, not just implied usage.

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