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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so safety profile is covered; the description adds value by enumerating the returned fields (name, address, fleet size, safety rating, insurance, crash history, OOS percentages) and by stating coverage scope ('all US carriers registered with FMCSA'). It does not disclose failure behavior, e.g. what happens with an unknown DOT number or when both identifiers are supplied.

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-loads the action and the identifier options, then the return payload, then triggers, then scope — a sensible order with no filler sentences. The return-field list and the list of example phrasings are long, but each item carries information an agent can match against a user query.

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?

Because there is no output schema, the enumeration of return fields is necessary and present, and the scope statement covers coverage. The gap is invocation correctness: with 0 required parameters, the description never says that at least one of dot_number or mc_number must be provided or how the tool behaves if both are given, which an agent needs to call it 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?

Schema coverage is 100%, so both parameters are already documented with types and examples. The description only adds that they are alternative lookup keys ('DOT number or MC number'); it does not say whether supplying both is allowed, which takes precedence, or that at least one is expected despite zero required parameters. Baseline 3 applies.

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 ('look up a trucking company, freight carrier, or motor carrier by DOT number or MC number') and enumerates the returned data, so the agent knows exactly what it gets. It does not name the overlapping FMCSA siblings (fmcsa_carrier_search, fmcsa_carrier_authority, fmcsa_safety_scores), so the boundary between a keyed lookup and those tools is left to inference.

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?

Supplies concrete trigger questions ('is this carrier safe?', 'check this DOT number', 'verify this carrier') plus a general fallback ('or any freight carrier lookup'), which gives a clear usage context. It stops short of exclusions — nothing says when to prefer fmcsa_carrier_search (name-based) or fmcsa_safety_scores over this one.

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