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

With no annotations, the description carries the full behavioral burden, and it does well by disclosing payment requirements, HTTP 402 behavior, finality of payments, and the fact that Fatstack never receives the funds. It also states conversion accuracy characteristics such as exact factors and correct temperature offset handling. It does not describe output format or error behavior, which prevents a higher score.

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 reasonably sized but repeats payment terms in both the outer text and the untrusted-provider content. The core functionality is buried inside the untrusted-provider block, and the opening is dominated by payment and trust disclaimers rather than the tool's primary 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?

The description covers the essential conversion categories, payment flow, and temperature exception, but it omits return-value details, accepted unit identifiers, and how `precision` is used. Given the lack of an output schema and only 25% parameter coverage, an agent would need additional discovery to use the tool fully 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?

Input schema coverage is only 25%, and the description does not meaningfully compensate. It does not explain the `to`, `value`, or `precision` parameters beyond the schema, and it does not enumerate accepted unit strings beyond the example already present for `from`.

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 core description clearly states the tool 'Converts between length, mass, volume, time, digital-storage and temperature units', which names a specific verb and resource. It also adds a useful behavioral distinction by noting temperature handles offsets correctly, and no sibling tool performs a similar function.

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 gives clear context that the tool is for unit conversion and lists the supported categories, so an agent can infer when to use it. It does not explicitly state when not to use it or name alternatives, but no sibling tool is a unit-conversion alternative, so the absence of exclusions is acceptable.

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