Upscale one image

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

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=false. The description adds real context beyond that: it warns that 'creative' 'can change small things' (a side-effect risk) and that the call 'Costs GPU time,' reinforcing the confirmation requirement carried in the schema.

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?

Four short sentences, front-loaded with purpose then the mode tradeoff. The index-ordering sentence and the trailing 'Costs GPU time' fragment are partly redundant with the schema, but nothing is bloated.

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 6-parameter mutation with annotations and full schema coverage, the description covers the purpose and the highest-risk parameter choice. With no output schema, it still omits where the resulting full-resolution image lands (e.g. download_job) and does not mention async/queue behavior, though 'wait' and 'speed' are fully documented in the schema.

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 100%, so the baseline is 3, but the description genuinely goes beyond it: the schema only says the type enum 'Defaults to subtle,' while the description explains the semantic tradeoff between subtle and creative, and it spells out the zero-based index-to-position mapping (0 top-left, 1 top-right, etc.) that the schema merely calls 'Which image, zero-based.'

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 specific verb (upscale) and resource (one image) plus a tightly scoped source: 'from a finished grid to full resolution.' That source scope is what separates it from siblings like vary_image, zoom_out, or pan_image, which operate on the same job/grid concepts.

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?

Gives an explicit when/when-not for the key decision point: 'subtle' is for faithful enlargement, while 'creative' is 'the wrong choice when the image is already right.' It stops short of routing the agent between this tool and other image-manipulation siblings, so no tool-level alternative is named.

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