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

Annotations already indicate that this is not read-only and not idempotent. The description adds useful context beyond those flags: a two-phase preview-then-execute flow, a fixed 100-credit cost, signed-quote validation, and preservation of siblings and prior revisions. It does not fully describe what execution returns, but the behavioral additions are meaningful.

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?

Three compact sentences with the core operation and execution flow front-loaded before scope exclusions. There is no filler, though '100-credit selected PNG revision' is slightly compressed and could be more explicit about what 'selected' refers to.

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 nested, two-phase mutation tool with no output schema, the description leaves notable gaps: it does not state what a successful execution returns, does not mention idempotency/retry behavior despite the idempotencyKey parameter, and only lightly sketches the request object's role. The dryRun parameter fills in some context, but a complete mental model of the execution response is missing.

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 high and already documents packId, componentId, quote, dryRun, and idempotencyKey. The description only adds minor semantic color around the signed quote and the 100-credit cost. It does not clarify request.revisionId, request.prompt, or referenceImageBase64 beyond what the schema provides.

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 clearly states the action: get a cost preview for a PNG revision, then pass a signed quote to execute. It also disambiguates scope by stating that SVG artwork editing is Phase 2 and not enabled by this tool. It does not name a concrete sibling like replace_ui_component_png, but the PNG-revision resource is clear.

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 intended two-step workflow is implied: request a preview, receive a signed quote, then execute. The description also explicitly excludes SVG editing. However, it does not explain when to prefer this tool over named alternatives such as replace_ui_component_png or revise_asset, and the approval/auth context is mostly deferred to the dryRun parameter.

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