upload_image

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

With no annotations, the description carries the behavioral burden. It usefully discloses that bytes are uploaded directly to COS without passing through the business server, that it returns image_url, and that it is free. However, it omits details like authentication requirements, file size limits, or overwrite behavior.

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 concise and front-loaded: it leads with the core action and return value, then adds use cases and the cost note. Every sentence earns its place without unnecessary elaboration.

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, the description covers the essential context: destination, return value, direct-upload behavior, cost, and use cases. It does not provide an output schema, but mentioning image_url is sufficient for a tool of this complexity.

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 100%, so both file_path and kind are already documented in the schema. The description adds little parameter-level detail beyond the schema, which is acceptable given the high coverage.

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 action—upload local images to COS—and the concrete return value (image_url). It also names two concrete use cases (reference image for video editing, or getting a URL before registration), which helps distinguish it from the many sibling upload tools.

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 context for when to use the tool: for video-editing reference images or for URL-first registration. It does not explicitly name alternatives or state when not to use it, but the use-case framing is sufficient guidance.

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