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

No annotations exist, so the description carries the full burden of behavioral disclosure. It only states the basic conversion intent and gives no details about supported unit codes, parsing behavior, error handling, or response format, leaving the tool's actual runtime behavior largely opaque.

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 extremely short and gets to the point immediately. The 'Speed:' prefix is redundant with the tool name, but the remaining sentence is economical and free of filler, which is appropriate for a simple conversion tool.

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?

With no annotations, no output schema, and overlapping sibling tools, a single sentence is not enough for confident invocation. The agent is not told which units are accepted, what the return value looks like, or why x402-speed should be chosen over x402-speed-convert or x402-units-convert.

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?

All three parameters have schema descriptions, so the baseline is 3, but those descriptions are essentially placeholder text like 'To to process' and 'From to process.' The main description adds the useful context that these are speed units, but it does not enumerate valid unit strings or explain the expected value format.

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 clear operation and resource: 'Convert between speed units.' This tells an agent the tool is for unit conversion. However, it does not differentiate it from near-identical siblings like x402-speed-convert or x402-speed-to-kph.

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 other conversion tools such as x402-speed-convert, x402-speed-to-kph, or x402-units-convert. No exclusions, prerequisites, or selection criteria are provided, so an agent must guess which sibling is appropriate.

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