photoshop_generative_expand

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

With no annotations, the description carries the full burden and does well: it lists preconditions (active document, generative_fill capability) and side effects (canvas enlarged with generated content). It doesn't explicitly flag reversibility/undo or rate/cost limits, which keeps it from a 5.

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?

Front-loaded with the core action, then labeled Use-when, Returns, Preconditions, and Side-effects blocks. Every line carries information with no filler or redundancy.

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?

No output schema exists, but the description documents the return shape (ok, summary, details with direction/prompt/wait) plus preconditions and side effects. An agent has everything needed to call it correctly.

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 schema already documents all four parameters including defaults and the document_id activation rationale. The description restates amount_px and direction semantics rather than adding new meaning, so baseline 3 applies.

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 and resource (extend canvas via Generative Expand) and describes the mechanism (enlarge by amount_px, fill with outpainting Generative Fill). Distinguishes it clearly from siblings like resize_image, crop_document, generative_fill, and generative_upscale.

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?

'Use when: outpainting, extending background, or expanding composition' gives clear triggering scenarios. It stops short of naming alternatives (resize_image, generative_upscale) or exclusions, so the routing is implied by the scenario rather than by explicit contrast with siblings.

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