Cancel Scheduled Message

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

The description adds valuable behavioral context beyond annotations: it clarifies that the tool cancels future scheduled messages or undoes a hold, and that cancellation is impossible after dispatch starts. Annotations already indicate destructiveness and idempotency, so this is not contradictory.

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?

The description is extremely concise with two sentences. The first sentence states the action, and the second provides a critical constraint. No unnecessary words.

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?

Given the simplicity of the tool (cancel a scheduled message) and the presence of an output schema, the description fully covers what the agent needs to know: what it does and the key limitation (cannot cancel after dispatch).

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 description does not need to add parameter details. The description does not repeat or expand on parameter meanings beyond the schema, which is acceptable but not exceptional.

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 uses a specific verb 'Cancel' or 'undo hold' and clearly identifies the resource as 'future scheduled message'. It distinguishes this tool from siblings like 'update_scheduled_message' by specifying the timing constraint ('before dispatch begins').

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 explicitly states when to use the tool (before dispatch begins) and when not to use it (cannot cancel after dispatch starts). It does not mention alternative tools, but the context of siblings is clear enough.

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