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

Goes well beyond the destructiveHint/idempotentHint annotations: discloses irreversibility, that recipients see a tombstone, that the actor's number appears online, and that unread messages in the conversation are silently marked read. These are non-obvious side effects an agent could not infer from structured fields.

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?

Front-loaded with the core action and the safety caveat, and every paragraph carries information. Slight redundancy between 'Revoke a message for everyone' and 'This is WhatsApp's delete for everyone', plus a grammatically awkward sentence about the number appearing online, cost it a point.

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 destructive, open-world action with an output schema available, the description covers what the agent must know: irreversibility, recipient-visible effects, hidden state changes, and the human-confirmation norm. Nothing material is missing.

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% and both parameters are documented in the schema, so the description needn't explain them. It adds no parameter-level meaning beyond the schema, which is the correct baseline for this coverage level.

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 specific verb (revoke/delete) and resource (a message) with explicit scope: 'for everyone in the conversation'. This distinguishes it from edit_text_message and edit_media_caption, which alter content rather than remove it.

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?

Gives a clear usage condition: confirm with a human before deleting anything a person has plausibly already read. It does not explicitly name alternatives (e.g., edit_text_message when the goal is correction rather than removal), so routing is implied rather than stated.

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