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

Annotations already declare idempotentHint=true, so the '重复拉黑 no-op' line partly restates structured data. However, the description adds value beyond the annotations by stating the login requirement and the concrete effects (mutual DM block plus automatic unfollow), which the annotations do not convey.

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?

One compact line, front-loaded with the login precondition, then effects, then usage scenario, then idempotency. Every clause earns its place with no filler.

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 single-parameter mutation with no output schema, the description covers the precondition (login), the behavioral effect, the intended scenario, and repeat-call behavior. Nothing an agent needs to invoke it correctly is missing.

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 there is only one parameter ('userId', documented as the user to block), so the schema already carries the parameter meaning. The description adds no syntax or format detail beyond it; 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 ('拉黑某用户') and immediately names the exact consequences (mutual DM disabled, auto-unfollow), which distinguishes it from siblings like unblock_user, ban_live_user, and report_content. An agent can identify the operation without opening the schema.

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 clear scenario trigger ('处理骚扰时用' – use when handling harassment), which is real usage context. It does not name an alternative or exclusion (e.g., report_content vs. block), so it stops short of full when/when-not routing.

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