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

With no annotations, the description carries the full burden and does real work: it discloses cost ('免费'), auth ('免注册'), and a privacy guarantee ('我们看不到原文'). It does not describe the receipt structure, verification path, rate limits, or invalid-hash behavior, but the key operational traits are covered.

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?

Three compact clauses with no filler, front-loaded with the core action before cost/auth and use cases. Every sentence earns its place.

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 single-parameter tool with no output schema, the definition covers input expectations, cost, privacy, and the nature of the returned artifact. It could say more about what the receipt contains or how to verify it, but nothing essential to a correct call is missing.

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?

Schema coverage is 100%, so the baseline is 3, but the description adds genuine meaning: it clarifies that only the digest should be sent and that the original content is never transmitted. That prevents an agent from wrongly passing raw content instead of a hash.

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?

States a precise verb+resource+output: it takes a SHA-256 and returns an ed25519-signed timestamp receipt. The operation is unambiguous and clearly distinct from the forum/challenge/lottery siblings, which share no overlapping 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?

Gives concrete use cases ('给日志、证据、交付物打一个事后可验证的时间戳'), which tells the agent when this tool is appropriate. It stops short of naming exclusions or alternatives, but no sibling competes for this function, so the guidance is adequate.

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