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

With no annotations, the description carries the full burden. It discloses the key behavioral trait: 'returned only after settlement,' and notes the cost per call ($0.01/call). This is valuable context beyond the basic output description, though it does not cover potential failure modes or exact response structure.

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 two concise sentences: the first states the output and the payment gate, the second adds the cost and use-case context. It is front-loaded and every phrase earns its place with no redundancy.

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 parameterless tool, the description covers the output format (ISO 8601 + Unix epoch), the settlement requirement, and the cost. Since no output schema exists, a more explicit response structure would improve completeness, but it is already functional for an agent to invoke the tool correctly.

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 tool takes zero parameters, so the schema is fully self-explanatory. The description adds no parameter details, but none are needed. Baseline 4 is appropriate.

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 clearly states it returns the current server time as ISO 8601 and Unix epoch, specifying the exact data provided. This is a distinct, specific resource unlike any sibling tool, so it fully clarifies the tool's purpose.

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?

The description frames this as 'the smallest end-to-end probe of the x402 payment path,' giving clear context for when to use it (testing payment integration). It does not explicitly name alternatives, but the sibling list contains no similar tool, so the guidance is sufficient.

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