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

Annotations only say readOnlyHint=true; the description adds genuine context beyond that: login is required, results are narrowed by the subject's display settings, public audience, and two-way blocking, and — most valuable — an empty list does not mean the person didn't participate, so the agent must not infer private activities. Return shape/pagination is unstated, which keeps it from a 5.

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?

Compact and front-loaded: auth requirement first, then scope, then the empty-result caveat. Every clause carries information; the only cost is that the density makes the visibility rules slightly hard to parse on first read.

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 read-only single-parameter list tool with no output schema, the description covers the essentials an agent needs to call it correctly: auth, visibility filtering, and correct interpretation of an empty result. Missing only pagination/result-shape hints, which is a minor gap here.

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% for the single required userId parameter, so the schema itself gives no semantics. The description only implicitly identifies it via '某人' (the person whose profile is being read), adding little about format, lookup, or whether it accepts non-user identifiers. With one obvious parameter this is adequate but thin.

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: read a person's publicly displayed participation activities, filtered by display settings, public audience, and mutual blocking. The scope ('公开参与活动' - public only) clearly separates it from own-activity listings such as list_my_activities, though no sibling is named explicitly.

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 real prerequisite ('【需要登录】') and an important non-obvious constraint that being the person themselves or an org admin does not widen the scope. However, it never names an alternative tool for the case where a broader view is actually wanted (e.g. list_my_activities for one's own full history), so the routing guidance is implied rather than explicit.

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