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

Annotations already declare destructiveHint=true and idempotentHint=true, yet the description adds real substance: this is a soft delete into Trash, reversible via restore_message for seven days, after which deletion is permanent. That lifecycle and the recovery window are exactly the behavioral facts an agent needs and cannot infer from annotations.

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?

Two sentences, no filler. The human-confirmation precondition and the Trash/recovery behavior are both front-loaded where an agent will see them before acting.

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 no explanation, and the description covers the remaining essentials for a one-parameter destructive tool: the confirmation prerequisite, the reversibility window, and the permanence deadline.

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 carries the burden, and it says only 'the exact message' without naming message_id, its UUID format, or how to obtain it. The parameter is largely self-evident for a delete tool and the schema supplies the uuid format, so this is adequate but not compensating for the coverage gap.

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 (delete) and a precisely scoped resource (a received email), which distinguishes it from the many sibling delete tools (delete_draft, delete_sent_message, delete_thread, delete_inbox). An agent can pick this tool without opening any 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?

Gives an explicit precondition — confirm the exact message with the human before deleting — and points to restore_message as the recovery path. It does not state when-not to use it (e.g., bulk cleanup vs delete_thread), but the routing context is clear.

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