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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive. The description adds meaningful behavioral context beyond them: the returned fields (operating authority, insurance and bond, suspension or revocation notices, red flags), dataset provenance for each flag, and the caveat that it is not a rating or vetting decision. No contradiction with 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?

Three front-loaded sentences cover purpose, return contents, and usage boundary with no filler. The most important selection constraints come first, and every sentence earns its place.

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?

No output schema exists, so the description usefully summarizes returned data and states the vetting caveat. It is close to complete for a read-only lookup, but it still gives no guidance on invalid-number handling or how it relates to the sibling batch and recent-notice tools.

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 description coverage is 100%, and the schema itself gives examples of both USDOT and MC number formats. The description repeats the lookup keys but adds no syntax, validation, or fallback behavior beyond what the schema already provides, making the baseline 3 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?

States a specific verb ('Looks up'), resource ('U.S. motor carrier or freight broker'), source ('FMCSA public records'), and identifiers ('USDOT number or MC number'). It does not name or contrast with the sibling tools check_carrier_list or recent_suspension_notices, so it misses full sibling differentiation.

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?

Gives explicit usage context ('Use before booking or paying a carrier or broker') and a clear boundary ('Not a rating or a vetting decision'). However, it does not say when to choose this over check_carrier_list or recent_suspension_notices, leaving alternatives unaddressed.

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