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

The description discloses important behavioral traits beyond annotations: the 10 MB limit and the side effect that calling the tool starts the sign-in flow and requires a connected Photo AI Studio account. This adds useful context that annotations alone do not provide.

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 compact and front-loaded: it states the purpose, workflow role, accepted inputs, size limit, and prerequisite/side effect in two short paragraphs. Every sentence contributes meaningful guidance, with no filler.

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 upload tool with no output schema, the description is complete: it states the return value (a URL), the input formats, the size limit, the account requirement, and the sign-in side effect. It also explains how this tool fits into the broader sibling-tool workflow.

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 input schema already describes both parameters clearly and fully, so the baseline is 3. The description adds the 10 MB limit and summarizes the base64 use case, providing extra value beyond the schema without repeating it verbatim.

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 states a specific verb and resource: 'Upload an image to the Photo AI Studio CDN and get back a URL.' It also differentiates from sibling tools by noting that generate_photo, edit_image, and create_video consume CDN URLs, so upload_image is the entry point.

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 clear when-to-use guidance: it explicitly says to start here before generate_photo, edit_image, or create_video, and explains the choice between public URL and base64 data. It does not explicitly state when not to use it, such as when a CDN URL is already available, but the workflow context is strong.

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