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

Beyond the readOnly/openWorld annotations, it discloses the entire execution model: $0.03 USDC on Base, the x402 handshake (402 → PAYMENT-SIGNATURE → delivery), that the tool call itself is free, and that payment occurs on the returned URL. That is exactly the non-obvious behavioral context an agent needs before committing.

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 resource and the question it answers, then price and payment mechanics. The title is restated verbatim in the first sentence and 'Free to call this tool; payment happens on the URL' slightly restates the preceding x402 sentence, minor redundancy.

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?

For a single-parameter, no-output-schema tool, it covers return shape ('returns the x402 URL to GET'), the payment sequence, and the decision context. An agent would not need anything else to invoke it and complete payment 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?

Only one parameter exists and schema coverage is 100%, so the schema already documents 'mc' as the MC/docket number. The description repeats that identity but adds no format guidance (e.g. numeric-only vs 'MC' prefix), so it adds little beyond structured data.

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 concrete verb and resource: a live FMCSA broker-authority lookup keyed by MC/docket number, framed as 'Is this broker real and allowed to arrange freight?' The broker-vs-carrier split is clear from the wording, which implicitly separates it from check_carrier_authority, though that sibling is never named as a contrast.

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 check a carrier or factoring agent runs before accepting a load from an unknown broker' gives a clear usage situation and audience. It stops short of explicit exclusions or pointing to alternatives such as check_carrier_authority or vet_load when the entity is a carrier rather than a broker.

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