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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=true, so the safety profile is covered structurally. The description adds only the single-image constraint and repeats the mode enum, leaving real behavioral questions unanswered: the tool appears asynchronous (siblings wait_images and generation_status exist) yet nothing says whether a job id is returned, and destructiveHint=true is never reconciled with an upscale operation.

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?

A single short clause with the modes and the exclusion front-loaded and no filler. Brevity here comes at the cost of substance rather than being wasteful, so structure itself is fine.

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 5-parameter, 20%-covered tool with no output schema and a likely async workflow, the description omits parameter meaning, return/status behavior, and any permission or delivery context. It is not adequate to invoke the tool confidently.

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 coverage is only 20% across 5 parameters. The description restates the operation enum values but says nothing about action (preview/auto/run), requestId, deliveryMode, or the image URL/data-URL input, so it does not compensate for the documented gap.

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?

States a resource (one image) and enumerates the four processing modes (x2/x4/anime/face), and explicitly carves out scope with 'not general editing', which separates it from editing-oriented siblings. 'Process' is generic, but the mode list plus the tool name upscale_image pin the purpose down.

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 phrase 'not general editing' is a genuine exclusion, but there is no positive when-to-use guidance and no routing to the plausible alternatives among siblings (generate_image, derive_image, wait_images). Usage is only implied by the mode names.

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