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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description still earns credit for disclosing return scope (no posted-videos list), which is a behavioral fact not expressed in the annotations or input schema.

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?

Three short clauses separated by semicolons: what it does, when to pick the sibling, and what is out of scope. Front-loaded with the action, zero 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?

A single required parameter fully documented in the schema, an output schema that carries return values, and annotations covering safety and openness leave nothing an agent needs missing. The description's only job, disambiguation, is done.

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 coverage is 100%, and the schema's url description already specifies the https://haokan.baidu.com/author/{id} format plus where to source profile_url values. The description's '按用户主页链接' adds no meaning beyond that, so the baseline of 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?

Names a specific verb+resource combination (fetch user profile by homepage URL) and immediately scopes it against the sibling that takes a user ID. Adding that it does not return a works list further separates it from haokan_get_user_posted_videos_by_profile_url without either schema being opened.

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 states the selection rule: use this when you have a profile URL, and switch to haokan_get_user_info_by_user_id when you only have an ID. The exclusion of works is implied rather than routed to the sibling that does return them, so the guidance is strong but not exhaustive.

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