search_images

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

No annotations are provided, and the description carries the full burden well: it discloses that API keys stay server-side in proxy mode, that the keyless fallback is restricted to CC0 commercially usable images, that source switching is only available in server mode, and roughly 12 results per page. These are operational traits an agent cannot infer from the 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?

Purpose and return shape are front-loaded, then mode behavior, then usage tips; every clause carries information. It is a dense single block with nested parentheses, which makes it slightly harder to scan than a short bulleted structure would be.

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?

There is no output schema, yet the description explains what comes back (thumbnails plus directly usable http(s) URLs) and what to do with it. Combined with the mode-dependent behavior and key handling, an agent has everything needed to call it and consume the result correctly.

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%, so the baseline is 3; the description adds real value by noting that query works with either Chinese or English content words (with examples) and that source is only meaningful in server mode. It doesn't expand on the page parameter beyond the schema's page-size hint.

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+resource (搜索在线图库的照片) and the concrete downstream use (给卡片配图), plus what it returns (缩略图和能直接使用的图片地址). It also distinguishes itself from the sibling import_stock_image, which is the tool that persists a selected result rather than searching.

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 splits the two operating modes: with DINGCARD_SERVER_URL configured it goes through the server-side proxy (Pixabay/Unsplash/Pexels/Openverse) and requires import_stock_image to get a stable URL; without it, results are direct Openverse CC0 links usable as-is. It even names where the returned URLs are consumed (create_poster_from_content image, image node src, page background).

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