phone_system_available_numbers

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

The description adds no behavioral context beyond the basic action. Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, so the safety profile is covered. However, the description does not mention any additional behaviors like pagination, limits, or that it returns a list, which are not implied by 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, concise sentence with no filler. It is appropriately front-loaded with the core action. It could be slightly more descriptive, but it is efficient for a simple operation.

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 has 9 parameters, a required countryCode, and no output schema, the description is too minimal. It does not explain the business context (e.g., searching for purchasable numbers), any response format, or why filters like MMS/SMS/voice matter. The user cannot fully understand the tool's purpose from the description alone.

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%, so all 9 parameters are already documented in the input schema. The description adds no additional meaning about the parameters or their usage, so a baseline score 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 'List available phone numbers' clearly states the verb (list) and resource (available phone numbers). It is specific enough to distinguish from other phone system tools by indicating the 'available' state, though it does not explicitly contrast with siblings like phone_system_active_numbers.

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 such as phone_system_active_numbers or phone_system_get_number_pool_list. There is no mention of prerequisites like needing a location ID or why one would search for available numbers.

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