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

Annotations already declare destructive=true and idempotent=true; the description adds concrete consequences beyond them – shared details are deleted immediately and nothing is sent afterwards – and notes the status_token is private. The two trailing sentences about being a listing service with no paid ranking have no bearing on this operation and dilute the behavioral signal.

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 useful content is front-loaded in the first three sentences. However, roughly half the text is unrelated marketplace boilerplate about listing versus referral services and paid placement, which costs space without helping an agent invoke this tool.

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?

With full schema coverage, an output schema, and annotations covering destructive and idempotent behavior, the description supplies enough to call this correctly and understand the consequence of deletion. Only the already-sent failure case and its error behavior are left unaddressed.

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 both parameters are already documented in the input schema. The description only adds the qualifier that status_token is 'private', which is marginal added meaning; baseline 3 applies.

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?

Names a specific verb and resource: cancel a message that has not yet been sent to the lawyer. The precondition ('not been sent') also implicitly separates it from status/introduction tools. It does not explicitly distinguish it from the sibling cancel_introduction, so it falls short of 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?

The opening clause gives a clear trigger condition ('when the person wants to cancel a message that has not been sent'). It does not name an alternative tool or state what to do if the message was already sent, so an agent must infer the exclusion.

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