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

Annotations cover safety (readOnlyHint=false, destructiveHint=false, openWorldHint=true, idempotentHint=false), so the bar is lower, and the description still adds value: the result is persisted ('Saved to the user's Network Builder') and a trial run is a one-time, consumed resource. It does not state what happens on repeated calls with the same name or any account-tier prerequisites beyond the Desk mention.

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 tight sentences, front-loaded with the core operation and scope before the persistence note and the pricing/trial caveat. No filler or restatement of the tool name.

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 describing returns and does so partly ('each leg's mode, cost, and transit time', or costless legs without a Desk plan). It still leaves open whether an identifier is returned, how the saved network is later retrieved, and what the total looks like.

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 baseline is 3, but the description adds genuine meaning beyond the schema: it explains the pricing/paywall consequence of use_trial_run ('otherwise legs come back without costs') and reinforces the 10-leg cap. Legs' internal fields (origin, destination, weight_lbs, commodity_type) are left entirely to the schema.

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 ('Price a supply chain of up to 10 legs ... and total it') and makes the scope explicit (factory-to-store, domestic or international, 10-leg cap). This clearly separates it from the single-mode siblings such as estimate_truckload_rate or estimate_ltl_rate, which price one lane rather than a totalled multi-leg network.

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 a concrete conditional for use_trial_run: Desk accounts get full costs, other accounts can 'spend the account's one-time trial run', otherwise legs return without costs. That is real when-to-use guidance, but it never routes the agent away from the single-mode estimate siblings for simple lanes.

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