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

Annotations already declare destructive=true, idempotent=true and openWorld=true, so the safety profile is partly covered. The description adds real value beyond that: it scopes the destruction ('The event and its completion data stay') so an agent can reassure itself the event isn't deleted, and it discloses the manage-token requirement.

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?

Three short sentences, each earning its place: effect, non-destructive scope, prerequisite. The core effect is front-loaded and there is 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?

For a two-param mutation with no output schema and full annotation coverage, the description supplies the essential side-effect and auth context an agent needs. It doesn't describe the response shape, which is a minor omission given no output schema exists.

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 both parameters (site_id, event_name) are already fully documented in the schema, including where to list valid values. The REST path 'DELETE /sites/{site_id}/events?name=' restates which parameter maps to what but adds no new semantic detail, so the baseline of 3 applies.

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 ('Remove the currency set for an event') plus the resulting state ('uses the site's default again'). This cleanly distinguishes it from the inverse sibling fathom_set_event_currency without needing to open either 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 clarifies the effect and the condition (reverting to site default) and states the prerequisite ('Needs a manage token for the site'). It never names the sibling set_event_currency explicitly, so the when-to-use-this-vs-that routing is implied rather than spelled out.

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