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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, and the description reinforces this with 'Purely a calculation — nothing is saved.' It also adds a real constraint beyond the annotations: equationId must belong to processId or one of postProcessingIds, and overrides change inputs, never the formula. It does not cover error behavior or performance, keeping it just short of the top.

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?

Front-loaded with the core action and return, then progressively narrower guidance (draft testing, then the alternative tool). Five sentences, none of which is filler, and the exclusion is placed last where it does not obstruct the primary call.

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 14-parameter, nested-object tool with no output schema, the description still tells the agent what comes back (price breakdown plus equation variables), that nothing persists, and how to compare draft vs live equations. The only gap is the pile of optional ids, which the 100%-covered schema handles.

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 coverage is 100%, so baseline is 3, but the description adds meaning the schema does not: equationId's role as a draft-equation test harness, the ownership constraint on it, and the conceptual distinction that variables override inputs rather than the equation itself. The remaining 11 optional ids 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?

Opens with a specific verb and resource — 'Price a part configuration on demand' — and states the return payload ('price breakdown plus the pricing-equation variables'). It explicitly separates itself from the sibling explainPrice, so an agent can route between them without reading either 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?

Gives concrete when-to-use conditions: a part not yet ordered, or testing a process/material/quantity/variable change. It also prescribes a specific workflow for equationId (call once with and once without to compare against live) and names explainPrice for the existing-order-line case.

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