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

Adds substantial context beyond the annotations: it requires the analytics scope, can hard-fail on stale connections pending reconsent, and clarifies there is no API call to trigger the sync (it happens implicitly once both resources exist). Annotations only cover read/write and open-world hints.

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 front-loaded in the first clause, and the remaining sentences carry prerequisites and downstream steps rather than filler. It is dense with nested parentheticals, which slightly taxes readability but each part earns its place.

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 mutation tool with no output schema, it covers the key operational context: required scope, reconsent failure mode, implicit sync behavior, and downstream tooling. It stops short of describing what the call returns or how to confirm success.

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 67%: eventName and countingMethod are already documented in the schema, and the description only adds illustrative example values for eventName. The 'property' parameter remains undocumented in both schema and description, so the description does not fully compensate.

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 and resource: marking a GA4 custom event as a key event, with concrete event-name examples. It also situates itself relative to siblings (create_google_ads_link, update_ga4_conversion_action) so an agent can identify it without opening a 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?

Spells out when to use it: together with create_google_ads_link as the prerequisite for Google Ads conversion sync, plus the follow-on step via update_ga4_conversion_action. It also names the exclusion condition — a connection made before the analytics scope was requested will refuse until reconnected.

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