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

No annotations are provided, so the description carries the full burden. It discloses nothing about behavior, input interpretation (2-D point pair), output format, or numeric handling — only a duplicated name.

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?

Extremely short, but this is under-specification rather than conciseness — the single sentence conveys no information and duplicates the tool name verbatim.

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?

A 4-parameter numeric utility with no annotations and no output schema requires the description to explain input pairing, coordinate convention, and return value. None of that is present.

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 nominally 100%, but the schema descriptions themselves are vacuous ('X1 to process', 'Y2 to process'), so effective parameter guidance is essentially zero. The description adds nothing beyond the schema, and the x1/x2/y1/y2 pairing semantics (which pairs with which) are never stated.

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 is a pure tautology, restating the name twice ('Distance2d: Distance2d') with no verb, resource, or scope. It gives an agent no way to distinguish it from siblings like x402-distance, x402-distance3d, or x402-manhattan-distance.

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 when-to-use guidance, no exclusions, no named alternatives. With dozens of sibling distance/geometry tools (x402-distance, x402-distance3d, x402-chebyshev-distance, x402-manhattan-distance), the absence of routing guidance is a serious gap.

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