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

Annotations declare readOnlyHint=true and destructiveHint=false, and the description does not contradict them. The description adds behavioral details: it excludes mismatched/unknown terms, keeps losses, separates quoted opportunities from invoice differences, and lists non-actions (does not fetch rates, verify documents, annualize savings, or book). This goes beyond the annotations, though it does not specify output format or error handling.

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 three sentences: the first states the core purpose, the second describes handling of mismatches and losses, and the third lists exclusions and a constraint. Every sentence adds value and is front-loaded with the main action. No wasted words.

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?

The tool has a complex input schema (array of objects with many required fields) and no output schema. The description explains what it does with inputs but does not describe the return format (e.g., list of differences, summary, or error handling). Given the complexity, the description should at least hint at the output structure, which is missing. The constraint 'up to 50 shipments' is in the schema but not emphasized in the description.

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 0%, so the description must compensate. It mentions 'invoice/quote amounts' (baseline_amount_usd, candidate_amount_usd) and 'explicit comparability evidence' (comparison_evidence), but it does not explain the enum fields (baseline_kind, candidate_kind, included_charges, service_requirements, shipment_requirements) or the source fields beyond what the schema already provides. The schema itself has descriptions for several fields, but the description adds little to parameter understanding.

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 states a specific action (calculate USD cost differences), a specific resource (up to 50 shipments using supplied amounts and evidence), and explicitly lists exclusions (fetch rates, verify documents, annualize, book). This clearly distinguishes it from sibling tools like compare_modes (mode comparison) and batch_quote (quotation).

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 implies usage: it requires supplied invoice/quote amounts and explicit comparability evidence, and it excludes mismatched/unknown terms. It also states what it does not do (fetch rates, verify documents, annualize, book), which hints at when to use other tools, but it does not explicitly name an alternative or provide a clear 'use this when...' directive. The constraint 'One candidate per shipment per call' further clarifies usage.

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