Set an item's image from a URL

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

Without annotations, the description carries the burden of disclosure. It adds meaningful context ('no upload involved') that prevents a common misunderstanding, and implies that the item's image is simply pointed to a URL. While it does not explicitly mention overwriting or side effects, the core behavioral trait is clearly communicated.

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 exceptionally concise: two sentences, front-loaded with the primary action and purpose, and every sentence earns its place. It contains no fluff or repetition.

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?

For a simple two-parameter tool with no output schema or nested objects, the description covers the essential aspects: what it does, when to use it, and a clear alternative. It is sufficient for an agent to select and invoke the tool correctly, though it could theoretically mention that it replaces the existing image.

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%, so the description must compensate. It adds value by clarifying that imageUrl should be an externally-hosted URL, complementing the 'uri' format in the schema. However, it does not add much insight into itemId, which remains straightforward. Overall, it provides some extra meaning but not comprehensive explanation.

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 the tool's function with a specific verb ('Points') and resource ('an item at an externally-hosted image URL'), and distinguishes it from the sibling tool upload_item_image. It is concise 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 provides usage guidance by stating when to use this tool (for external URLs) and when to use the alternative (upload_item_image for local/binary images). This is a clear and direct usage differentiation.

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