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

The description discloses the core computation (returns the Dec 31 23:59:59 timestamp) and the default behavior for the current year. With no annotations, the description carries the full burden, but it omits the output format (Unix epoch vs ISO string) and timezone context, and the 'given date' mention is inconsistent with the schema's zero parameters.

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?

A single, well-structured sentence that front-loads the purpose and includes the key detail of the exact timestamp. No wasted words.

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?

The tool is simple and zero-parameter, so the definition is mostly adequate. However, the output format and timezone are unspecified, and the contradiction between 'given date' and the empty schema leaves ambiguity about whether a date can actually be supplied.

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 schema has no properties, so there are no parameters to document; the baseline is 4. However, the description introduces an optional 'given date' that the schema does not define, which could mislead an agent into attempting to pass a date argument. This inconsistency reduces the score.

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 the operation: return the end-of-year timestamp (Dec 31 23:59:59) for a given date or the current year. It is specific about the verb and resource. However, it does not distinguish itself from similar sibling tools like x402-year-start or x402-end-of-day, and the 'given date' clause conflicts with the empty input schema.

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 implies when to use the tool: whenever an end-of-year timestamp is needed, with a default to the current year. It gives a clear scenario but provides no explicit guidance on when not to use it or which alternative sibling tool to prefer, which is needed given the large family of date/time tools.

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