search_ebay_by_image

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

With no annotations, the description carries the burden and delivers real behavioral facts: the API is experimental, the source inputs are mutually exclusive (one and only one), and results include a contact sheet. It omits operational details such as rate limits, cost, or what happens if multiple sources are supplied.

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 tight sentences with the core constraint front-loaded and zero filler; the parenthetical notes earn their place by clarifying input formats. Slightly dense for a 13-parameter tool, but nothing is wasted.

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 covers return values and the description covers the source-selection rule, which is the main complexity. However, for a 13-parameter tool with zero schema documentation, the filtering and pagination parameters are left entirely unexplained, which is a meaningful gap for an agent composing a query.

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 0% across 13 parameters, so the description must compensate, and it does for the most important ones: image_path (local file), image_url, similar_to_item (item id or URL, uses main photo), and category_id's relevance impact. The remaining filters — aspects, condition, buying_options, min/max_price, sort, limit, offset, contact_sheet — get no explanation beyond their names, and "aspects" in particular is opaque.

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?

"Visual-similarity search (eBay's experimental searchByImage)" states a specific verb and a distinct resource, and the visual-similarity framing inherently separates it from the keyword-based sibling search_ebay. An agent can pick this tool without opening the schema.

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 gives the critical selection rule — supply exactly one of image_path, image_url, or similar_to_item — and a quality tip (category_id greatly improves relevance). It stops short of explicitly naming when to prefer this over search_ebay or get_ebay_item_photos, so there is no full when-not guidance.

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