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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real behavioral scope beyond that: this is a pure, optional ID-conversion utility that returns only the ID and is NOT a required prerequisite for other calls, which prevents an agent from expecting enriched user data or chaining it unnecessarily.

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?

Two sentences, zero waste, with the core action stated first and the routing caveat second. Everything stated 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?

An output schema exists, so return values need not be explained, and annotations cover the read-only/open-world profile. Purpose, usage conditions, and the non-prerequisite caveat are all present for a one-parameter conversion 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?

Schema description coverage is 100%, and the schema already spells out the 29-character lowercase hex requirement and the invalid inputs (24-char user_id, red-book number, nickname, profile URL). The description's '完整加密用户 ID' only lightly reinforces that, so the baseline 3 applies.

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 specific verb and resource: convert a complete encrypted user ID into a stable user_id. It also implicitly separates itself from siblings like xhs_get_user_info_by_user_id / _by_profile_url by clarifying that it only performs ID conversion and does not fetch user data.

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?

Explicitly gives the when: '仅需单独转换 ID 时使用' (use only when you need the ID converted on its own). It also gives the when-not and the alternative path: to query user info or posts, use the existing user ID or profile link directly without calling this tool. This is exactly the when/when-not/alternative guidance the dimension asks for.

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