Get a number

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

Annotations only report readOnlyHint=false and idempotentHint=false, but the description adds the critical side effect: 'THIS CHARGES the reseller balance immediately (pay-per-code).' It also discloses the 20-minute auto-refund and early-release refund behavior, giving the agent a clear picture of cost and reversion semantics before calling.

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 three sentences: action first, then the charge warning, then the follow-up workflow. Every sentence carries necessary information, and it does not waste tokens repeating 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 description covers the full purchase workflow, including charging, refunds, and polling via order_id. Because there is no output schema, a more explicit statement of the exact return shape (e.g., an object containing phone_number and order_id) would make it fully complete, but the current wording provides enough for correct invocation.

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 the schema already documents all four parameters. The description only generically references service and country and does not add per-parameter meaning, so the baseline 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 opens with a concrete action: 'Buy a phone number for a service in a country and return it.' This clearly distinguishes the tool from siblings like get_balance, check_order, and wait_for_otp, even though the title 'Get a number' is vague on its own.

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 clear lifecycle guidance: buy the number, then poll with wait_for_otp using the returned order_id, and optionally release() early for a refund. It does not explicitly state when not to use this tool or name alternative purchase-like siblings, so it stops short of full exclusion guidance.

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