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

Annotations already declare destructiveHint=true and readOnlyHint=false. The description adds valuable context by explaining that this is a revocation, not a true deletion, and that modern clients honor it. This goes beyond the annotations and gives the agent a clearer mental model of the effect.

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, front-loaded with the main action, and immediately adds the crucial revocation nuance. Every sentence earns its place with no filler.

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 an output schema present and annotations covering destructive behavior, the description explains the core behavior (revocation) and the schema covers all parameters. It lacks explicit mention of prerequisites or edge cases (e.g., can only delete your own message unless sender is provided for admin), but those are in the schema, so it's reasonably complete.

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 100%, and each parameter already has a clear description (chat, sender, account_id, message_id). The tool description adds no additional parameter-specific guidance, so it doesn't exceed the baseline for high coverage.

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 states a specific action ('Delete a WhatsApp message for everyone') and resource (WhatsApp message), and clarifies the subtle revocation behavior. It distinguishes from siblings like wa_edit_message or wa_react by focusing on deletion for everyone, and the nuance of revocation vs true delete is explicitly explained.

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 description clearly says 'for everyone' which indicates the intended use case, but it doesn't explicitly contrast with alternatives like wa_edit_message or wa_react, nor does it state when not to use it. The sender parameter for admin use is only implied via schema, not described in the usage context.

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