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

Annotations already establish readOnly, idempotent, and non-destructive behavior. The description adds valuable behavioral context beyond that: it returns exact prices when fixed, min/max ranges when variable, does not promise accuracy, and requires no API key ('[free, no key]'). No contradiction with annotations.

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?

Three focused sentences with no filler. The first sentence front-loads the core purpose, the second explains the exact-vs-range behavior, and the third adds a crucial caveat plus auth note. Every sentence earns its place.

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 description covers what the tool returns, how pricing varies, and the free/no-key requirement. With no output schema, the return-value description is useful and mostly sufficient. Minor gaps remain around expected operation naming and the exact output shape, but the tool is simple enough that this is not a major deficiency.

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 documents params as 'the same request body you would pass to the operation,' and the description reinforces the 'proposed call' idea. However, the operation parameter is only a bare string with no allowed values or format, and the description does not elaborate on how operations are specified. Schema coverage is exactly 50%, so the description only partially compensates.

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 names a specific verb ('Return') and a precise resource: cost, latency, and success-probability estimates for a proposed call before execution. This clearly distinguishes it from siblings like get_outcome, get_status, or verify_company_record, which address different concerns.

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 clearly signals this tool is for pre-execution estimation ('before execution') and cautions that accuracy is not promised, directing the user to cost_range. It does not explicitly name alternatives or state when not to use it, but the context is clear enough given the sibling set.

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