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 add one genuinely useful piece of context: the free trial limit of 5 calls per signed wallet, which signals an auth/payment requirement. It says nothing about what happens after the trial is exhausted, expected input format (the schema types 'value' as a string), or whether output is rounded.

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?

Two short clauses, front-loaded with the conversion statement followed by the pricing note. The 'Knots To Kph:' prefix partially restates the name, but it is compact and nothing is padded.

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 trivial one-parameter converter the description covers intent and cost, which is most of what an agent needs. It is still thin on the input contract for a string-typed numeric field and on post-trial behavior, but no output schema is needed for such a simple return value.

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 description coverage is 0% for the single 'value' parameter, so the description should compensate and does not. It never states that 'value' is the knot measurement, nor whether it accepts decimals, negatives, or an optional unit suffix despite being typed as a string.

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 and resource: 'Convert knots to kph', which is unambiguous about the input and output units. It does not explicitly name the inverse sibling x402-kph-to-knots, but the directional naming makes the distinction self-evident.

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?

Usage is only implied: an agent can infer this is the tool for knots→kph conversions rather than kph→knots, but there is no explicit 'use this when' statement or reference to alternatives such as x402-speed-convert or x402-units-convert. For a single-purpose converter this is close to adequate but still leaves routing to inference.

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