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

With readOnlyHint/openWorldHint already declared, the description adds meaningful context beyond the annotations: per-call pricing ($0.011 USDC via x402) and the fact that store=true creates a 7-day share link rather than returning data inline. It does not describe latency, failure modes, or output format, but the cost and side-effect disclosure is substantive.

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 dense sentences, front-loaded with the core operation before the store option and cost. Every sentence carries information, though the pricing sentence is somewhat packed and could be split cleanly.

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 7-parameter tool with no output schema, the description covers purpose, mask semantics, store behavior, and cost, which is decent. It is still incomplete on the input-modality choices (image_url vs image_base64, mask_url vs mask_base64) and the strength parameter, gaps an agent must guess at.

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 43%, so the schema documents only prompt and store; the description reinforces both plus the mask convention. It adds nothing about the image/mask URL vs base64 alternatives or the meaning of the 0-1 'strength' parameter, which remain undocumented in both places.

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 gives a specific verb and resource ('Edit part of an image') and even explains the mask convention ('white = area to repaint'), which is more than most image tools state. It does not, however, distinguish itself from the close sibling image_edit, so an agent cannot tell the two apart from the text alone.

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 lists concrete use cases (remove objects, replace backgrounds, add items), which implies when the tool is appropriate, and explains the store option's trade-off. There is no explicit when-not guidance or named alternative such as image_edit, leaving the sibling selection ambiguous.

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