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

With no annotations, the description carries the full behavioral burden. It discloses that conversions use 'exact international definitions' and states the x402 price per call, which adds useful context. However, it does not describe return format, precision guarantees, or error behavior.

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 a single, front-loaded sentence stating purpose and units, followed by a brief pricing clause. Every part is relevant and nothing is wasted.

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 simple conversion tool with no annotations and no output schema, the description covers the purpose, supported units, precision stance, and cost. It omits return value details, but those are minor for a straightforward converter.

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%, but the schema descriptions are trivial ('From', 'To', 'Value') and the enum values are cryptic abbreviations. The description lists the full unit names (metric tons, kilograms, etc.), directly mapping to the enum values for 'from' and 'to', which adds meaningful semantic clarity.

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 states a specific verb (Convert), the resource (weight and mass units), and enumerates all units covered. This resource focus cleanly distinguishes it from sibling converters like area, length, or temperature without needing to name them.

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?

There is no guidance on when to use this tool versus alternatives, no prerequisites, and no exclusions. The description only states what it does, leaving usage entirely to inference.

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