waha_check_number_exists

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

With no annotations, the description must carry behavioral disclosure. It states the action ('check') which implies a read-only operation, but it does not disclose what the tool returns (e.g., boolean, error behavior), whether it requires an active session, or any edge cases like invalid numbers. The description is minimal but not misleading.

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, concise sentence that gets straight to the point. It is front-loaded with the action and resource, with no redundant words or 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?

For a simple check tool, the description is minimally adequate but not fully complete. Since there is no output schema, the description should clarify the return format or possible outcomes, which it does not. It also omits context about session requirements or error handling, making it incomplete for an agent to invoke with full confidence.

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 input schema already covers the single parameter 'phone' with a clear description and an example. The tool description adds no extra meaning to the parameter, so it relies on the schema. With 100% schema coverage, a baseline of 3 is appropriate.

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 clearly states the tool's function: 'Check if a phone number has a WhatsApp account.' It uses a specific verb ('Check') and resource ('phone number') and distinguishes itself from sibling tools like waha_get_contact or waha_get_contact_about, which retrieve detailed contact information rather than just existence.

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 no explicit guidance on when to use this tool versus alternatives. It implies a use case (verifying WhatsApp existence) but does not mention exclusions, prerequisites, or alternatives such as waha_get_contact or waha_send_text. This leaves the agent to infer appropriate use from the name alone.

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