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

With no annotations, the description carries the full burden and does so richly: privacy guarantees (never discloses identity the caller didn't already have), result semantics (cluster_id returned only when linked), error behavior (invalid_arguments when the two numbers are equal, free; free not_found on unresolved numbers), and pricing behavior (paid, pricier, billed the same for 'not linked').

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?

Front-loaded with the core purpose and the key differentiator, then layers in semantics, routing, and pricing. Every sentence carries real information, though the parenthetical cross-references make it longer than strictly necessary.

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?

With no output schema and no annotations, the description fully covers what an agent needs: return semantics (cluster_id only when linked), error cases and cost, and the alternative tool. Nothing required to invoke it correctly is missing.

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 0%, so the description must compensate, and it does: it explains that both usdot_number_a and usdot_number_b are caller-supplied, must differ, and must resolve in carrier_identity_cluster. It does not document the value format, but the behavioral constraints it adds go well beyond the bare titles.

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?

States a specific verb and resource: it confirms or denies that two specified carriers share an identity cluster. It explicitly distinguishes itself from check_carrier_identity and screen_carrier_identity, so an agent can select it without opening any schema.

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?

Explicit when-to-use: when you ALREADY SUSPECT two carriers are linked, as the lower-risk alternative to the removed linked_carriers field. It names the alternative (check_carrier_identity) and the condition that selects it ('who is linked to this carrier?'), giving clear routing.

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