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

No annotations are provided, so the description carries the full burden of disclosure. It reveals nothing about side effects, return format, invocation behavior, or safety. For all an agent can tell, this could be a read-only computation or a destructive operation.

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 short, but this is under-specification rather than conciseness. There is no useful content to front-load because no meaning is conveyed at all.

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 parameters, no annotations, no output schema, no title, and a tautological description, the definition provides nothing that equips an agent to select or call this tool. Comparted against thousands of vaguely similar siblings, it is completely inadequate.

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?

The input schema has zero parameters, which is anomalous for a tool named 'distance3d' that logically requires coordinates to compute anything. The description does not clarify whether no arguments are needed or how inputs are otherwise supplied, leaving an agent unable to invoke it correctly.

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 'Distance3d: Distance3d' is a pure tautology that merely restates the tool name with no verb or resource. It never states that this computes the distance between two points in 3D space or anything else about its function.

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 whatsoever about when to use this tool versus any alternative. Among siblings like x402-distance2d, x402-manhattan-distance, x402-chebyshev-distance, and x402-geo-distance, the agent receives zero information to choose correctly.

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