12306-MCP

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behavioral traits: it returns the current date (not time), uses Shanghai timezone, returns in yyyy-MM-dd format, and is designed for relative date parsing. The description doesn't mention error conditions or performance characteristics, but covers the essential behavior well for a simple utility.

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 perfectly concise and well-structured. Two sentences cover purpose, timezone, format, and primary use case with zero wasted words. Every sentence earns its place by providing essential information.

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 0-parameter tool with no annotations and no output schema, the description provides excellent context: purpose, timezone, format, and use case. It doesn't need to explain return values since the format is specified. The only minor gap is not explicitly stating this is a read-only operation, though that's implied by '获取' (get).

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 has 0 parameters with 100% schema description coverage. The description appropriately doesn't discuss parameters since none exist, but does mention the implicit 'current' aspect of the date retrieval. This exceeds the baseline of 3 for high schema coverage by providing context about what 'current' means in terms of timezone.

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' (get current date) with specific details about timezone (Asia/Shanghai, UTC+8) and return format (yyyy-MM-dd). It distinguishes itself from sibling tools which are all about train/station/ticket queries, making this a unique date utility tool.

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 when to use this tool: '主要用于解析用户提到的相对日期（如“明天”、“下周三”），提供准确的日期输入' (mainly used to parse relative dates mentioned by users like 'tomorrow' or 'next Wednesday' to provide accurate date input). It doesn't explicitly mention when NOT to use it or name specific alternatives, but the context is sufficiently clear.

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