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

Annotations already indicate readOnlyHint=true and destructiveHint=false. The description adds useful context by listing the specific cost components included (duty on freight, capital cost in transit, lost profit) and disclosing the extra output: the weekly lost profit at which the routes cost the same. This goes beyond what annotations provide.

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?

Two sentences with no filler. The main purpose is front-loaded, the key distinction from a freight-quote comparison is stated, and the additional breakeven output is clearly presented in the second sentence.

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?

For a tool with 10 parameters but no output schema, the description explains the core computation and the notable additional return value. It does not detail the full output format, but it gives enough context for an agent to understand what the tool produces and what inputs are conceptually involved.

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. The description does add conceptual meaning by connecting duty, capital cost, and lost profit to the calculation, but it does not materially improve parameter-level understanding beyond the schema descriptions.

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?

The description uses a specific verb and resource pair: 'Compare air and sea freight on total landed cost.' It clearly distinguishes this from a single-mode estimator like estimate_landed_cost by emphasizing the comparative nature and the 'rather than on the freight quote' framing.

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?

The description conveys the intended use case—comparing two freight modes on total landed cost—and implicitly rules out using it for a single-mode estimate. However, it does not explicitly name alternatives such as estimate_landed_cost or state when not to use this tool, leaving some selection inference to the agent.

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