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

Adds substantial behavior beyond the annotations: the call is side-effect free, returns a preview and a confirmation link, and requires merchant action on that page to take effect. This meaningfully softens the readOnlyHint=false framing without contradicting it, since the underlying operation is a write gated behind human confirmation. The 'money is integer minor units (cents)' sentence is a stray detail, as no price parameter exists.

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 short sentences, front-loaded with the action, then the preview semantics and the merchant gate. Tight overall, but the money-in-cents sentence earns nothing here because the tool takes no monetary field, making it minor noise in an otherwise lean definition.

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 three-parameter, fully documented schema with no output schema, this covers what an agent still needs: that the call is a non-mutating preview and that the real change happens on a merchant confirmation page. Return behavior is described inline rather than requiring an output 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 schema already documents url (formats, 10 MB cap, digital-product consequences) and name (defaulting to the address's name). The description adds no parameter-level meaning, and its only data-format remark concerns money, which is not among the parameters. 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: 'Add a digital file to a product.' The schema note that 'a product with a file is digital' further clarifies the effect, and the phrasing distinguishes it from products_add_image, which handles visual media. It does not explicitly name that sibling, but the object (digital file attached to the product) is unambiguous.

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 clear operational context for when to reach for this tool: it never performs the change itself, it returns a preview plus a confirmation link, and only the merchant on that page can commit. That tells an agent this is the proposal step in a two-step flow rather than a direct mutation. It stops short of naming alternatives (e.g., media_upload or products_add_image) or saying when not to use it.

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