Change Draft Schedule

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

Annotations cover safety and idempotency, and the description adds value beyond them: required scopes (mailbox.read, email.send), mandatory optimistic concurrency via expected_revision and expected_schedule_version, and the state-dependent failure 'Cancellation fails once sending has begun'. Those are precisely the operational facts an agent cannot infer from readOnlyHint=false / idempotentHint=true.

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?

Four short sentences, zero filler, with the core action and the 'only when the user asks' constraint front-loaded before auth and concurrency details. Every clause carries information an agent needs.

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 state-mutating scheduling tool with an output schema, the definition covers auth, concurrency, cancel semantics, and the failure boundary. Minor gaps remain: behavior on revision/version conflict is left entirely to the schema, and mailbox_id targeting is not mentioned in the description.

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 coverage is 100%, so the baseline is 3, but the description adds the reason the two expected_* fields must be passed (they are concurrency guards the caller must supply) and the meaning of scheduled_for=null as cancellation. That is genuine semantic value beyond the field-level descriptions.

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?

The description names a specific verb pair and resource: 'Reschedule or cancel a saved draft send'. That is unambiguous and clearly a distinct operation from update_draft or send_draft. It stops short of naming a sibling tool for contrast, so it isn't quite a 5.

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?

There is a real gating condition ('only when the user asks') plus an in-tool disambiguation (scheduled_for=null cancels, otherwise reschedules). However there is no guidance on when to use this versus update_draft or delete_draft, nor any statement of exclusions beyond the sending-started case.

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