活动签到。
用户到达活动现场后，通过此工具完成签到。支持手机号/用户ID/签到码三种方式。
Args:
activity_id: 活动 ID
phone: 手机号（用于签到，需与报名时一致）
user_id: 用户 ID（已登录用户）
code: 签到码（现场扫码获取，或主理人提供的签到口令）
Returns:
JSON 字符串，包含签到状态和签到时间
| Name | Required | Description | Default |
|---|---|---|---|
| code | No | 签到码，现场主理人提供 | |
| phone | No | 签到人手机号 | |
| user_id | No | 用户 ID，不传时用当前会话用户身份 | |
| activity_id | Yes | 活动 ID |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
Input schema / properties / activity_id / descriptionAdded value: +"活动 ID"Input schema / properties / code / descriptionAdded value: +"签到码，现场主理人提供"Input schema / properties / phone / descriptionAdded value: +"签到人手机号"Input schema / properties / user_id / descriptionAdded value: +"用户 ID，不传时用当前会话用户身份"Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It discloses that a return value includes check-in status and time, and that phone must match registration, but it omits important behavior such as whether check-in is idempotent, what happens if already checked in, and what authorization/permission requirements exist.
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 front-loaded with the purpose and then structured into Args and Returns sections. It is appropriately sized and has no wasted text, though the Args section partly repeats schema descriptions.
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 check-in mutation with no annotations, the definition covers purpose, methods, parameters, and a basic return shape. However, it lacks important edge-case behavior such as duplicate check-in handling, authorization requirements, and failure modes, leaving gaps for an agent to infer.
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 baseline is 3. The description adds value beyond the schema by noting that phone must match the registration record and that code can come from an on-site scan or the organizer's check-in token.
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 states a specific verb+resource: '活动签到' (activity check-in), and clarifies it occurs after the user arrives at the event. This implicitly distinguishes it from sibling register_event, but it does not explicitly name or contrast with that alternative.
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?
It clearly says to use this tool when the user has arrived at the event, and it lists three supported methods (phone, user_id, code). It gives clear context but does not state when not to use it or explicitly compare with alternatives like register_event.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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