datetime-mcp-server

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

The description adds valuable behavioral context beyond annotations. Annotations indicate read-only, non-destructive, non-idempotent, and closed-world hints, but the description elaborates with specific traits: '该工具始终返回当前时间，每次调用结果可能不同' (always returns current time, results may differ per call) and '返回的是服务器本地时间' (returns server local time). This clarifies the non-idempotent nature and time source, enhancing transparency without contradicting annotations.

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 well-structured and appropriately sized. It starts with a clear purpose statement, followed by sections on format placeholders, usage examples, and notes. Each sentence adds value: no redundancy with schema or annotations, and information is front-loaded for quick understanding. The length is justified by the detailed formatting instructions and examples.

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?

Given the tool's low complexity (1 optional parameter, no output schema), the description is complete. It covers purpose, usage, parameters with examples, and behavioral notes. Annotations provide safety context, and the description fills in gaps like time variability and server specifics. No output schema exists, but the description implies string return values through examples, which is sufficient for this simple tool.

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 description significantly enhances parameter semantics beyond the input schema. Schema coverage is 100% with a clear description of the 'format' parameter, but the description adds detailed format placeholders (e.g., yyyy, MM, dd), usage examples (e.g., 'yyyy-MM-dd' -> '2026-03-11'), and default behavior ('如果不指定格式，默认返回 "yyyy-MM-dd" 格式' - if no format specified, defaults to 'yyyy-MM-dd'). This provides practical guidance that complements the schema.

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 tool's purpose: '获取当前日期和时间，支持自定义格式化' (Get current date and time, supports custom formatting). It specifies the verb ('获取' - get), resource ('当前日期和时间' - current date and time), and distinguishes it from potential siblings by mentioning formatting support. No siblings exist, but the description is specific enough to stand alone.

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 provides clear context for usage: it explains when to use the tool (to get current datetime with optional formatting) and includes a '注意事项' (notes) section clarifying that it returns server local time and results vary per call. However, it lacks explicit alternatives or exclusions (e.g., when not to use it), as there are no sibling tools, so it doesn't need sibling differentiation but could mention use cases more broadly.

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