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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered; the description adds the valuable non-obvious constraint that deletion is conditionally blocked. It does not state whether the deletion is permanent or whether related mailer_logs are affected, which is the remaining behavioral gap for a destructive tool.

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 with the core action first and the preconditions immediately after; no filler or repetition of the title.

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?

An output schema exists, so return values need not be explained, and the preconditions cover the main failure modes. What is missing is the fallback path for the blocked cases and any note on permanence, which matters for a destructive operation.

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% and both parameters are documented in-schema, including that event_id comes from search_events. The description adds no meaning beyond the schema, so the baseline 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 ('Delete a mailer') that clearly separates it from create_mailer, update_mailer and read_mailers. It does not explicitly distinguish itself from the sibling deactivate_mailer, which is the nearest ambiguous alternative for an agent holding an active mailer.

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 concrete blocking conditions — active mailers cannot be deleted, and some waitlist/registration kinds cannot be deleted once mailer_logs exist — which tells the agent when the call will fail. It stops short of naming the alternative action (deactivate_mailer) for the active-mailer case, so the agent must infer the fallback.

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