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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is lower. The description adds real context beyond them: sort order, the returned field set, the auth requirement ('需要有效 Key，匿名不开'), and the cursor pagination contract (pass the nextCursor from the previous page).

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?

Dense but organized: purpose and returned fields are front-loaded, then parameters, then the usage trigger and auth note. Every clause carries information, though the parameter list is compressed into semicolon fragments rather than fully unpacked.

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?

With no output schema, the description usefully enumerates returned fields and explains pagination and the auth gate, which is what an agent needs to call it correctly. Remaining gaps are the from/to format and limit bounds, both minor for a read-only list 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 0%, so the description must carry the load. It explains slug (required), q (fuzzy search on host user identifier), and cursor (pass the prior page's nextCursor), but only bare-mentions from/to and limit without stating format, date semantics, or the limit ceiling (max 200).

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 (访客会话列表 for a 岗位), the sort order (最近优先), and enumerates the returned fields (session_id、宿主用户标识、轮数、时间). It implicitly routes detail-lookup to a separate tool via '再拿 session_id 看明细', distinguishing it from get_session_log.

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 a concrete when-to-use trigger ('想看最近都服务了哪些人用它') and the follow-up step of taking session_id to a detail tool, plus the prerequisite that a valid Key is required and anonymous access is disabled. It stops short of naming the sibling tool explicitly, leaving the routing slightly implicit.

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