GA4: Create key event

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=true, so the mutation safety profile is covered. The description adds the useful 'formerly conversion' framing but does not disclose required permissions, idempotency, or behavior when the event does not yet exist.

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 well-formed sentence that front-loads the core action and tacks on a clarifying example. No wasted wording, though it is arguably under-specified rather than richly concise.

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 simple 3-parameter, non-destructive write with a fully documented schema and no output schema, the definition is minimally adequate. It omits permission prerequisites and edge-case behavior that an agent calling a GA4 admin mutation would benefit from.

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 schema already documents all three parameters including the countingMethod enum. The description's 'generate_lead' example mirrors the schema's eventName example, adding no meaning beyond it.

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: 'Marks an event as a key event', and clarifies the legacy term 'conversion'. An agent knows exactly what the tool does, though it does not explicitly distinguish itself from sibling ga4_list_key_events.

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?

Usage is implied by the naming and example (mark a conversion-worthy event), but there is no explicit when-to-use, when-not-to-use, or prerequisite guidance such as requiring admin access to the property.

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