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

No annotations are provided, so the description carries the burden. It does add genuine behavioral context beyond the schema: conversions use 'exact definitions' (precision claim) and there is an x402 payment requirement of $0.001/call in USDC on eip155:8453, which an agent must know before calling. It still omits what the response looks like or error behavior on invalid units.

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 sentences, purpose front-loaded, no filler. The pricing clause is slightly bolted on with an em-dash but it is decision-relevant, so 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 three-required-parameter converter with no annotations and no output schema, the description covers purpose, supported units, conversion precision, and cost. The only minor gap is not stating the return shape (number vs unit-tagged string), which is largely implied.

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% so the baseline is 3, but the description goes beyond it by spelling out the five unit codes (kmh, mph, ms, kn, fts) as full names — 'kilometers per hour, miles per hour, meters per second, knots and feet per second' — which decodes the otherwise opaque enum values.

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 (convert) and resource (speed units) and enumerates all five supported units, so an agent can distinguish it from its siblings (temperature, length, weight, volume converters) without opening the schema. The scope is unambiguous.

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 explicit when-to-use guidance and no routing to alternatives beyond the implied 'this is the speed one'. The description never says when to pick this over, say, a general unit tool or a sibling converter — usage is only inferred from the tool name.

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