Order (assign) a number

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

Annotations only indicate non-readOnly and non-destructive. The description adds critical behavioral context: ordering costs money (purchase and recurring charges), requiring user confirmation. It also discloses possible error types (TN_ALREADY_ASSIGNED, etc.), significantly beyond annotation info.

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?

Four sentences, front-loaded with action, then cost warning, workflow, and errors. No redundant or irrelevant information. Very concise 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?

Although no output schema exists, the description provides good context: mentions workflow, errors, and cost implications. However, it does not explain what the tool returns on success (e.g., the ordered number object). Minor gap.

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% with descriptions for all 3 parameters. The description adds minor value: specifies tn format as '10 digits or 11 digits with leading 1'. No additional semantics beyond schema, so 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 clearly states 'Procure a telephone number from upstream inventory and assign it to your account.' It uses a specific verb ('order' / 'assign') and resource ('telephone number'), and distinguishes from siblings like num_search (find candidates) and num_bulk_order (bulk ordering).

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 explicitly instructs to confirm the number with the user first due to cost, references num_search for finding candidates, num_update_voice/sms for post-order configuration, and num_bulk_order for bulk ordering. It also lists common errors, providing clear when-to-use and alternative guidance.

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