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

Annotations already declare the operation as read-only, idempotent, and non-destructive, and the description adds substantial behavioral context: it recomputes from actual configuration, compares against stored quotedPrice, reports newer pricing, and warns that returned variables may be overrides. It does not cover permissions or output format details, but the behavioral picture is unusually complete.

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 key purpose and scope are front-loaded, and every sentence adds substantive guidance about recomputation, overrides, or reconciliation. It is somewhat dense and long for a one-parameter tool, but the length is justified by the complexity of price explanation rather than filler.

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 still explains what is returned: price breakdown, pricing-equation variables, comparison to stored quotedPrice, and newer-pricing status. It also names the exact sibling tools needed to interpret the variables, making it complete for an agent to call and use the result.

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?

The schema has 100% description coverage for the single requisitionId parameter, and the description only restates that this is an existing requisition/order line. The schema already carries the lookup hint, so the description does not add meaning beyond what structured data provides; baseline 3 is appropriate.

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 first sentence states a specific verb ('Explain') and resource ('existing requisition/order line costs'), and the description distinguishes this from the hypothetical path by naming generateQuote. An agent can tell exactly what this tool does without opening the schema.

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?

It explicitly directs hypothetical/what-if parts to generateQuote and explains how to reconcile returned variables using describePricingEquationApi(includeSource=true) and query materialPrices. This gives clear when-to-use and when-not-to-use guidance with named alternatives.

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