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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), so the bar is lower. The description adds genuinely useful non-schema behavior: each call consumes one estimate against the account's monthly FreightFA allowance, and the result is a directional benchmark rather than a binding rate. It does not discuss accuracy limits, currency, or turnaround.

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 short sentences, all front-loaded: what it does, what it returns, what it costs. No filler and nothing an agent must hunt for.

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 does tell the agent the result is a directional benchmark rather than a firm quote, and it discloses the quota cost. Missing details about the response shape (rate value, currency, breakdown) keep it short of a 5, but it is adequate for a fully-specified read-only estimation tool.

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%, so the schema already documents all four parameters including units and null semantics. The description adds no parameter-level detail beyond naming the tariff method, so the 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 (estimate), resource (less-than-truckload rate), and even the pricing basis (FreightFA's CzarLite-basis tariff calculator). This cleanly distinguishes it from the many sibling estimators such as estimate_truckload_rate, estimate_intermodal_rate, and estimate_rail_rate.

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?

"Returns a directional benchmark for planning" implies the appropriate context (early-stage planning rather than binding quotes), but it never states when to choose this over estimate_truckload_rate or estimate_intermodal_rate for a given shipment, nor any prerequisites beyond the schema's required fields.

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