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

Annotations already declare destructiveHint=true, readOnlyHint=false, and non-idempotent behaviour, so the safety profile is covered elsewhere. The description adds internal routing context (the server selects the upscale path), but it never explains what the destructive hint actually means here, e.g., whether the original image is replaced or a new asset is created, nor the cost or latency.

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?

Two short sentences, with the usage trigger front-loaded and no filler. Every clause carries information an agent needs before invoking the tool.

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?

An output schema exists, so return-value detail is unnecessary, and the single-parameter surface is fully covered. However, for a mutation flagged as destructive and non-idempotent, the description leaves unclear whether the original image survives, which is a meaningful gap for correct invocation and user warning.

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 would be 3, but the description adds real meaning: the generation ID alone is sufficient and the image is retrieved server-side, so the agent knows not to hunt for extra inputs.

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: make an existing RoomLab image 4K. That clearly separates it from the sibling tools, which are room-editing/render operations rather than upscales, though no sibling is named explicitly.

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?

It gives an explicit trigger condition ('when the user asks to make an existing RoomLab image 4K') and implies the input must already exist in RoomLab. There is no guidance on when not to use it or what to do instead when the image does not exist yet, so it falls short of a 5.

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