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

The description adds substantial behavioral context beyond the annotations: calling the tool produces a preview and confirmation link rather than an immediate mutation, and only the merchant can complete the action on that page. There is some tension with readOnlyHint=false because 'calling this changes nothing' sounds read-only at invocation time, but the overall workflow is a write proposal, so this is not a hard contradiction.

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?

The purpose and confirmation flow are front-loaded and useful, but the sentence 'Money is integer minor units (cents)' is irrelevant to an image-adding tool and appears to be template leakage. That wasted sentence lowers the score despite otherwise efficient structure.

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 tool with no output schema, the description explains the key return behavior: a preview and confirmation link, plus who can complete the change. It does not cover image constraints or failure cases, but the schema already documents url and alt semantics.

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 100%, including detailed guidance for url, product, and alt. The description adds no parameter-level information, so the baseline of 3 is appropriate.

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 first sentence states a specific verb and resource: adding a picture to a product. It is clear enough to distinguish from general product editing, but it does not explicitly differentiate from sibling media_upload or products_edit. The stray money sentence adds noise but does not obscure the core purpose.

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?

Usage is implied by the purpose, and the confirmation-flow sentence hints at when the tool is appropriate. However, there is no explicit guidance on when to use this versus media_upload or products_edit, and the media_upload prerequisite appears only in the schema, not in the description.

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