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

The description goes well beyond the annotations by disclosing login requirements, the fact that only the signup overlay is written, that file-type answers must not be written here because doing so would overwrite uploaded file records with text, that sensitive fields are intentionally not memorized, and that written values are not echoed back for privacy. No contradiction with the annotations is present; these are valuable behavioral details.

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 densely structured with clear sections (何时用, 组合链, 口径/坑), front-loading the most important usage context and then covering edge cases. Every sentence earns its place; there is no filler or repetition.

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 write tool with no output schema, the description is complete: it tells the agent when to use it, how it fits into the signup flow, what limitations apply, what not to write, and what the response will not contain (values are not echoed). The agent has everything needed to select and invoke it correctly.

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 adds essential parameter guidance beyond the schema: the key must be the stable cross-activity key returned by get_signup_activity/get_signup_gaps and must not be self-invented. It also clarifies that only text values are accepted, which reinforces the value parameter's semantics and prevents misuse even though the nested schema already names key and value.

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 job: writing user-provided reusable signup information into a cross-form coverage layer so future signups auto-fill it. It uses a specific verb ('更新'/'写入') and resource ('报名资料覆盖层'), and explicitly differentiates itself from update_my_profile, which modifies the main profile rather than the signup overlay.

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 explicit when-to-use guidance with realistic examples ('我微信是 xxx', '团队 3 个人', '所在城市杭州'), and says this tool is for casually given reusable info. It also gives a clear combination chain (get_signup_gaps → ask user → write here → submit_signup won't ask again) and an explicit exclusion: profile/company/product changes must go through update_my_profile.

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