search_images

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

With no annotations, the description carries full burden. It discloses that the tool searches multiple providers, returns specific fields (preview URL, download URL, dimensions, author, attribution link), and warns against hotlinking. However, it does not mention rate limits, authentication requirements, or any side effects, which would make it fully transparent.

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?

The description is a single paragraph but packs essential information without redundancy. It is concise and front-loaded with the main purpose, though it could be slightly more structured (e.g., bullet points for return fields).

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 must cover return values, which it does by listing preview URL, download URL, dimensions, author, and attribution link. It also explains the workflow with the sibling tool. For a search tool, this is fairly complete, though it lacks details on pagination or error handling.

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 baseline is 3. The description adds value by explaining how to use the download URL (pass to download_image) and mentions that English queries yield better results and that color filter support varies by provider, going beyond the schema definitions.

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 clearly states it searches free stock photos on Pexels, Unsplash, and Pixabay. It distinguishes from the sibling tool download_image by specifying that search results should be passed to that tool for placing images. The purpose is specific and unambiguous.

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 description explicitly states when to use this tool ('when the project needs a real photo and the client has NOT provided their own images') and when not to ('Prefer client-provided photos when they exist'). It also gives a tip about English queries and directs the agent to use download_image for placing images, which is excellent guidance.

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