whatsapp_check_phones

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

With no annotations, the description must disclose behavioral traits. It mentions input format ('country code, no '+'') but fails to specify if the operation is read-only, has rate limits, or returns detailed status per number. No side effects or authorization needs are discussed.

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 extremely concise, using one sentence to state purpose and a brief parameter hint. Every word adds value without redundancy, making it efficient for an AI agent to parse.

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?

Given the tool's low complexity and one parameter, the description provides minimal context. It covers the input format but omits details about the output (despite an output schema existing). No information about response structure or error handling is included.

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 has 0% description coverage, so the description's hint ('phones: list, country code, no '+'') adds some value by specifying formatting expectations. However, it remains ambiguous (e.g., whether numbers must be international format) and does not cover all nuances.

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 verb ('Check') and resource ('if phone numbers are on WhatsApp'), making it easy to understand its core function. However, it does not differentiate from sibling tools like whatsapp_search_contacts, which might overlap.

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?

No guidance is provided on when to use this tool versus alternatives, nor any context on prerequisites or limitations. The description simply states what it does without any usage instructions.

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