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

Annotations already cover destructive, read-only, and idempotent behavior. The description adds the 'returns its final status' behavior and the leased/replied restriction, providing context beyond the annotations. It is consistent with the annotations and adds value while remaining concise.

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 two sentences long, front-loaded with the primary purpose and the key restriction, and ends with the return value. Every sentence justifies its place; no extra wording is present.

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?

The core behavior is described, but the 'as' parameter is undocumented and the exact meaning of 'final status' is unspecified (e.g., what statuses can be returned, how failures are surfaced). Since output schema is absent, that responsibility falls on the description. Overall it is adequate but incomplete for an agent to fully predict the tool's side effects and outputs.

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%. The description implicitly refers to message_id as the target message ('Cancel my queued message') but never names or explains the parameter. More importantly, the 'as' parameter is entirely unexplained and its role is ambiguous. With zero schema coverage, the description should compensate by explicitly tying parameters to the operation, which it fails to do.

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 clearly states the operation: withdrawing a message you sent that is still queued, with an explicit state condition ('not yet leased'). It distinguishes from siblings like bus_ack and bus_send because it uniquely targets queued unleased messages and says so directly.

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 gives an explicit condition for use: only for messages that are still queued and not yet leased, and explicitly excludes messages already leased or replied. It doesn't name specific alternative tools (e.g., bus_nack for leased messages), but the boundary conditions alone are sufficient for an agent to select this tool correctly for the described scenario.

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