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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds only the diagnostic framing ('when a report shows zero conversions'); it says nothing about pagination, result size, or behavior for an unknown property_id. With annotations carrying the main burden, a 3 is appropriate.

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 sentence, front-loaded with the resource and its returned fields, then the usage triggers. No filler.

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?

There is no output schema, so the description usefully compensates by naming the returned fields (event name, counting method, custom flag). Combined with annotations covering the read-only profile and a fully documented single parameter, this is nearly complete; only return-shape details like counts or ordering are unaddressed.

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?

There is a single required parameter with 100% schema description coverage, so the schema already explains that property_id comes from list_connected_accounts. The description adds no syntax, format, or validation detail beyond that — baseline 3 when the schema does the work.

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 the specific resource (GA4 key events/conversions) and enumerates the fields returned — event name, counting method, custom flag — which is more concrete than a bare 'list' verb. The pairing with the sibling ga4_create_key_event makes the read intent implicit from the name, but the description itself never explicitly says it lists all key events on a property.

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 two concrete trigger conditions: before creating a key event, and when a report shows zero conversions. That is clear usage context, though it states no exclusions or alternatives (e.g. when to prefer ga4_report instead).

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