get_phone_number

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

With no annotations, the description carries the full burden for behavioral disclosure. 'Get information' implies a read-only operation, but it does not explicitly state that there are no side effects, whether authentication is required, or what happens if the number is not configured. The behavior around the optional 'fields' parameter (e.g., default return set) is also left undisclosed.

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, tightly written sentence that front-loads the action and resource, then lists representative outputs. No redundant words or filler, making it highly efficient and well-structured.

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 is simple with one optional parameter, and the schema covers parameters, so the description is mostly adequate. However, it lacks explanation of what 'configured' means in terms of which number is targeted, and how the fields parameter affects the response, leaving some contextual gaps for an agent deciding how to invoke it.

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 schema provides 100% coverage of the only parameter ('Specific phone number fields to retrieve') and enumerates all accepted values. The description adds minimal value by mentioning a few example fields, but these are already in the enum, so it does not significantly enhance understanding 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 clearly states the action ('Get information') and the specific resource ('configured WhatsApp Business phone number'), which distinguishes it from sibling tools like list_phone_numbers (which enumerates numbers) and get_waba_account (which targets the WABA). It also lists key data points (display number, verified name, quality rating, status), making the tool's purpose unambiguous.

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 compared to list_phone_numbers or get_waba_account. There is no mention of whether to leave fields empty for default behavior or how to filter results, leaving the agent to infer usage from the sibling names and schema.

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