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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the agent knows this is a mutating operation. The description adds important behavioral context: the tool requires explicit confirmation before sending, and it emphasizes the need for recipient context and exact content. This goes beyond the annotations by warning about the irreversible nature of sending a message. No contradiction with annotations.

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 a single sentence that front-loads the action ('Send a WhatsApp text or template') and immediately states the critical precondition. Every word earns its place; no fluff or repetition of schema details.

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 tool has an output schema, so return values are covered. The description covers the key behavioral requirement (confirmation) and the mutating nature. It doesn't mention rate limits or specific error cases, but for a send operation with annotations and schema, the description is sufficiently complete. The confirmation requirement is the most critical context and it's present.

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 67%, with 'confirmed' and 'idempotencyKey' already described in the schema. The description adds meaning by tying the 'confirmed' parameter to the explicit confirmation requirement and by framing the operation as a write that needs idempotency. The 'message' parameter's structure is well-defined in the schema, so the description doesn't need to repeat it. The description adds value beyond the schema.

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 verb and resource ('Send a WhatsApp text or template') and adds a critical precondition ('only after confirming the conversation, recipient context, and exact content'). It distinguishes itself from read/list tools in the sibling set, though it doesn't explicitly name an alternative for sending. Clear enough for an agent to know what the tool does.

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 gives explicit when-to-use guidance: only after confirming conversation, recipient context, and exact content. This is a strong usage constraint. However, it doesn't mention when not to use it or name alternatives (e.g., no sibling send tool exists, so this is less critical). The guidance is clear but not exhaustive.

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