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

Annotations already flag destructiveHint=true and idempotentHint=false, so the safety profile is covered; the description earns credit for going beyond them by disclosing blast radius ("everywhere it is kept"), exactly what is destroyed (text and media) versus preserved (status, price, timeline, redacted_at), and irreversibility. It does not state permission requirements or what happens if the message is not yet finished.

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?

One front-loaded sentence with no filler: the destruct scope comes first, the preserved fields second, irreversibility last. 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?

With one fully described parameter, no output schema, and annotations covering the safety profile, the description supplies the essential scope and irreversibility. It stops short of covering edge cases an agent might hit — redacting an unsent/in-progress message, or whether a second call on an already-redacted message errors.

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 parameter is fully documented in the schema (msg_... format), so per the high-coverage baseline a 3 applies. The description adds no meaning about the id beyond what the schema already gives.

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?

States a precise verb (empty/redact) and a specific resource (a finished message's text and media), and adds the retention rule (status, price, timeline kept, redacted_at set) that an agent needs to distinguish it from a plain delete. It never names delete_message explicitly, so the differentiation from that close sibling is inferential rather than explicit.

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 phrase "a finished message's" implies a precondition (message must be finished/sent) and the retention clause hints this is the choice over delete_message, but neither the when-to-use condition nor the when-not-to-use / alternative is stated. An agent must infer that delete_message is the alternative for full removal.

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