Preview a port-in

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

Annotations already indicate readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds value beyond annotations by stating that no project is created, that it groups results by SPID, and lists possible errors (NO_ACTIVE_CUSTOMER, INVALID_PAYLOAD, VALIDATION_ERROR, GATEWAY_UNAVAILABLE). This provides additional behavioral context not present in 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 concise with three sentences, each serving a distinct purpose: explaining the core function, providing usage guidance with alternative, and listing possible errors. It is front-loaded with the most critical information and has no unnecessary wording.

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 only one parameter with full schema coverage, annotations present, and no output schema, the description is complete. It covers purpose, usage context, alternatives, and error conditions, leaving no essential gaps for an agent to invoke the tool correctly.

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 input schema covers 100% of the single parameter 'tns', describing it as a free-form list of 10-digit NANP numbers. The description does not add new semantic meaning beyond the schema, but the mention of errors like VALIDATION_ERROR indirectly hints at parameter validation. Since schema coverage is high, a baseline 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 clearly states the tool runs an instant Telique-backed portability preview for a list of TNs, grouped by losing carrier SPID. It distinguishes itself from the sibling tool port_preview_transfer by specifying that this preview is for numbers to be ported in, not for on-net transfers.

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 says to use this tool BEFORE port_create_request to see portability and carrier info. It also provides a clear alternative: for numbers already on-net (WARP-to-WARP), use port_preview_transfer instead. This gives clear context on when and when not to use the tool.

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