Photos Preview Url

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

With no annotations, the description carries the full behavioral burden. It usefully discloses an authentication prerequisite—a browser cookie is usually required—but does not state whether the operation is read-only, whether the returned URL expires, or other side effects. This is a minimum-viable disclosure with clear gaps.

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 front-loaded sentence with zero waste. It states the purpose and the key prerequisite immediately, which is appropriate for a tool of this scope.

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?

The output schema means return values need not be explained, and the description covers the essential purpose and the browser-cookie prerequisite. It leaves some minor gaps, such as the meaning of the 'size' enum and how the cookie should be obtained, but it is largely sufficient for correct invocation.

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 83%, so the schema already documents most parameters. The description adds no parameter-level meaning beyond noting the cookie requirement, which is not a parameter. Baseline 3 is appropriate when the schema does the heavy lifting.

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 gives a specific verb and resource: '获取照片预览 URL' (get photo preview URL). This clearly distinguishes it from sibling tools like photos_detail or photos_search by naming the preview URL as the resource, but it does not explicitly state how it differs from those siblings in the text itself.

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?

The parenthetical '通常需浏览器已登录 cookie' supplies a prerequisite context (usually requires a browser logged-in cookie), but there is no explicit guidance on when to choose this tool over alternatives such as photos_detail or photos_raw_request. Usage is implied rather than stated.

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