Order Number

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

Discloses that only received messages are billed, lists return fields (phone number, activation_id, etc.), and warns about duplicate rejection. Annotations do not contradict; description adds valuable behavioral context beyond readOnlyHint/destructiveHint flags.

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 concise (a few sentences) and well-structured: starts with main purpose, lists return fields, explains parameter flexibility, gives usage guidance, notes billing, and ends with an important warning. No redundant information.

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 no output schema, the description thoroughly enumerates return fields and provides context on pricing, expiration, and cancellation. It also references prerequisite (check_price) and follow-up (check_sms) tools, making the tool's role in the workflow clear.

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 coverage is 100%, but the description adds meaning: explains auto-resolution of names from cached catalog, that max_price protects against price changes, and that quality_factor defaults to 50 (balanced). This goes beyond the schema's basic descriptions.

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 (rent), the resource (virtual phone number), and the context (via Platfone API for given country and service category). It distinguishes from sibling tools by referencing check_price and check_sms for related tasks.

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?

Explicitly instructs to 'Use check_price first to verify cost and availability' and 'Use check_sms with the activation_id to poll for incoming SMS'. Warns against duplicate calls with 'Only call this tool once per order. Never call it multiple times in parallel — duplicate orders will be rejected.'

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