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

Annotations already declare destructiveHint=true and idempotentHint=true; the description goes beyond them by explaining what is preserved (a cancellation receipt) and the exact race window that determines success or failure. It does not specify what error or state is returned when cancellation is attempted too late, which keeps it from a 5.

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 zero filler, and the precondition (owned, pending, before claiming) is front-loaded before the idempotency and failure-window notes.

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 single-parameter mutation whose safety profile is already covered by annotations, the description supplies the timing constraint, ownership requirement, idempotency confirmation, and receipt behavior. The only meaningful gap is how a too-late attempt surfaces (error vs. status change), which the absence of an output schema leaves unresolved.

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?

The single required parameter dispatch_id has 0% schema description coverage; only its regex pattern is documented. The description implies the identifier refers to a dispatch request but adds no format, sourcing, or retrieval guidance, so it neither compensates for the gap nor repeats anything harmful.

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 (cancel), a specific resource (an owned pending dispatch request), and a scope/precondition (before worker claiming). It is clearly distinct from siblings like send_ecard, publish_ecard, or get_ecard_status, which handle creation, dispatch, or read-only inspection.

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?

It states both when to use it (owned, pending, not yet claimed) and when it's too late (once processing begins). It does not name an alternative to use in the too-late case, such as get_ecard_status, so it falls short of full routing guidance.

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