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

With no annotations, the description carries the full behavioral burden, yet it discloses nothing about input units, the formula applied, behavior on zero/negative values, or whether inputs are parsed as numbers given the string typing. It only implies a pure computation, which is the bare minimum.

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?

It is short, but the brevity is under-specification rather than conciseness: the second clause merely repeats the first, so half the text earns no place. Nothing beyond the tool name is front-loaded.

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 output schema, no annotations, and vague parameters, the description needed to state the computation (½ × base × height), accepted input format, and units. None of this is present, so an agent cannot confidently call it for anything but the most trivial case.

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 100%, so the baseline is 3, but the schema text ("Base to process", "Height to process") is placeholder filler and the description adds no clarification that these are the triangle's base and height or in what units. The description neither compensates for nor worsens the weak schema wording.

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 text "Triangle Area: Area of triangle" is essentially a restatement of the tool name/title, with no verb, scope, or distinguishing detail. It never clarifies which triangle-area formula is used (base×height/2 vs. Heron) nor differs meaningfully from siblings such as x402-triangle-heron or x402-area.

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 when-to-use guidance, no mention of when a different sibling (e.g. x402-triangle-heron for three-side input, x402-area for generic area) should be chosen instead, and no stated preconditions. For a crowded math sibling group, a routing sentence was warranted.

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