get_friends_with_category

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

With no annotations, the description carries the full burden, and it does disclose one useful behavioral fact: this is a NapCat extended interface ('NapCat 扩展接口'), signaling it may not exist on every OneBot implementation. Beyond that it says nothing about read-only nature, return shape, or pagination, though for a zero-parameter read tool the omission cost is modest.

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?

A single compact sentence with no wasted text and the core purpose front-loaded. It is arguably under-specified rather than over-long, but structurally it is clean.

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?

No output schema exists, so the description would ideally hint at the return structure (categories containing friends), which it does not. For a simple no-arg read tool this is a gap but not a severe one, since the agent can invoke it without additional risk.

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 tool takes zero parameters, which is the baseline-4 case; there are no argument names or formats that the description could clarify or that it leaves ambiguous.

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 and resource: retrieving a friend list organized by friend categories ('按好友分组归类的好友列表'). The grouping qualifier implicitly distinguishes it from the sibling get_friend_list, but it never names that sibling explicitly, so the differentiation is left to inference.

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?

There is no when-to-use guidance and no mention of the obvious alternative get_friend_list. The agent must deduce from the word '分组归类' that this is the grouped variant rather than the flat list, but nothing in the text says when one should be chosen over the other.

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