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

Annotations already establish a safe read-only operation, and the description adds important behavior: output can be either CSA BASIC percentiles or a public safety summary, with 'always available' summary and interpretation guidance (higher percentiles worse, lower OOS rates better, national averages included). This transparently manages agent expectations beyond the structured hints.

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 front-loaded with the core purpose and output split, then gives concrete example questions and interpretation rules. Each sentence earns its place; no filler.

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, the description carries the burden of explaining returns, and it does so explicitly: either CSA BASIC percentile scores (rare) or a public safety summary listing crash and OOS metrics, plus interpretation and national averages. For a one-parameter read-only tool, nothing essential 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?

The single dot_number parameter is clearly referenced in the purpose statement ('by DOT number'), which confirms its role, but the description adds no format, example, leading-zero, or validation guidance beyond the schema's integer/positive constraint. Given 0% schema description coverage, more compensation would be better, but the parameter name and one-line mention keep this minimally usable.

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 clear verb and resource: 'Get safety information for a trucking company by DOT number.' It distinguishes the safety-evaluation purpose from carrier lookup/search siblings implicitly through 'safety scores' and the detailed output description, but it never names an alternative tool.

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?

Provides explicit use cases ('is this carrier safe?', 'how many crashes?', 'should I hire this carrier?') and states it is for 'any trucking safety evaluation.' It does not name when-not-to-use or alternative siblings such as fmcsa_carrier_lookup/compare, so it falls short of a full 5.

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