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

Annotations already declare readOnlyHint/idempotent/destructiveHint, so the safety bar is low; the description still adds real value by explaining what each finding contains (named lever, exact engine results vs directional figures, applied method). 'Read-only and free' is partly redundant with the annotations, but the 'free' claim and the finding-shape disclosure are net additions.

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 lever inventory is front-loaded and each sentence carries information, but the long comma-separated list of levers is heavier than an agent needs for selection. Still, no sentence is pure filler and the routing and safety notes come after the main purpose.

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 an output schema present, the description need not explain return values, and annotations cover safety. It supplies purpose, usage contexts, the alternative for pricing, the nature of the findings, and the cost of the call — everything an agent needs to select and invoke it correctly.

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?

One parameter at 100% schema description coverage, so the schema already fully documents calculation_id and even points at the tools that return it. The description adds only indirect parameter context ('the gap to a supplier quote when one is on file'), which is the expected baseline for a fully documented single-param tool.

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 (list cost-reduction levers for a calculation) and enumerates the levers concretely rather than abstractly. It also distinguishes itself from the sibling that prices a lever ('use preview_cost'), so an agent can separate it from the other analysis tools without opening a 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 clear intended contexts ('brief a redesign or a supplier negotiation') and an explicit alternative with its condition ('To price one of them, use preview_cost'). It does not, however, contrast itself against the other analysis siblings such as explain_cost or get_cost_breakdown, so the routing is helpful but not exhaustive.

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