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

No annotations are provided, so the description carries the full behavioral burden, yet it discloses almost nothing. It implicitly suggests a pure deterministic computation, but the formula (d1*d2/2), units, and behavior on missing/zero inputs are all unstated.

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 single sentence is redundant: 'Rhombus Area: Area of rhombus' says the same thing twice. There is no waste from length, but there is no useful content either.

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 two-parameter math tool with no output schema and no annotations, the description should at least state the computation and output (area) or the required diagonals. It leaves the agent to infer everything except the topic.

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 both parameters (diagonal1, diagonal2) are documented in the schema; baseline is 3. The description adds no meaning beyond it, not even noting that the diagonals combine via the d1*d2/2 formula.

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 just restates the tool name ('x402-rhombus-area' → 'Rhombus Area: Area of rhombus'), which is a tautology. It does convey the resource (rhombus area) but adds no distinguishing detail and doesn't differentiate from siblings like x402-kite-area or x402-parallelogram-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?

No guidance on when to use this tool versus the many other area tools, no prerequisites, no exclusions. Nothing beyond the bare purpose statement.

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