search_images

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

With no annotations provided, the description carries full burden and does well by disclosing key behavioral traits: it specifies the default return format ('small base64-encoded JPEG images') and the alternative behavior when return_url is true ('return image URLs, title, shapes, and other metadata'). It doesn't mention rate limits, authentication needs, or potential costs, but provides substantial operational context.

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 appropriately sized with three sentences that each serve distinct purposes: stating the core function, providing usage context, and describing output behavior. It's front-loaded with the most important information. While efficient, the third sentence could be slightly more concise by integrating the return_url behavior more directly.

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?

Given the tool's moderate complexity (6 parameters, 1 required), no annotations, and no output schema, the description does well to cover the essential context: purpose, usage scenarios, and output format behavior. It doesn't explain error conditions, rate limits, or authentication requirements, but provides enough information for basic effective use of this search tool.

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?

The schema description coverage is 100%, so the baseline is 3. The description adds minimal parameter semantics beyond the schema - it mentions the default base64 encoding and that return_url changes the output format, but doesn't elaborate on other parameters like tbs, location, gl, or hl. The schema already documents these thoroughly, so the description adds limited extra value.

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 explicitly states the tool's purpose as 'Search for images across the web, similar to Google Images' with specific examples of what can be found (photos, illustrations, diagrams, charts, logos). It clearly distinguishes from sibling tools like search_web or search_arxiv by focusing exclusively on visual content, making the purpose highly specific and differentiated.

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 provides clear context for when to use this tool: 'when you need to find photos, illustrations, diagrams, charts, logos, or any visual content' and gives examples like 'illustrate concepts, locating specific pictures, or discovering visual resources.' However, it doesn't explicitly state when NOT to use it or name specific alternatives among siblings, which prevents a perfect score.

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