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

Annotations only declare the generic mutation profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false), but the description adds the confirm=false preview / confirm=true execute gate, the required analytics.edit scope, and remediation for permission errors. This is exactly the behavioral detail beyond annotations that an agent needs.

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?

Multi-segment but front-loaded, leading with the core action before enumerations and the SAFETY note. The middle sentence on post-marking behavior is mildly verbose yet earns its place by explaining downstream impact; overall message density is appropriate.

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 an output schema present, the description covers the essentials: what it does, the preview/execute gate, auth scope, and parameter meanings. Return values are rightly omitted since the output schema exists; only the precise format expectations for event_name/property are left unstated.

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%, so the description must carry parameter meaning, and it does for most: it defines the counting enum values (ONCE_PER_EVENT default | ONCE_PER_SESSION), explains the confirm flag's semantics, routes property to ga4_list_properties, and gives event_name examples. Only event_name and property lack precise format details.

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 a GA4 event as a CONVERSION (key event)' with concrete examples ('generate_lead', 'purchase', 'sign_up'). This clearly distinguishes it from read/list siblings like ga4_list_conversions, so an agent can route correctly without opening the 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?

The description conveys when to use it (to promote an existing event into a counted conversion) and points to ga4_list_properties for resolving the property ID. It stops short of naming a competing/alternative tool or when-not-to-use conditions, so it is clear context rather than full routing guidance.

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