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

The description states "Calling this changes nothing: it returns a preview of what would change and a confirmation link," while the annotations declare readOnlyHint=false and idempotentHint=false. A no-side-effect preview call is by definition read-only and idempotent, so the description directly conflicts with the structured safety/idempotency signals an agent relies on.

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 description is short, front-loaded, and the operational facts (preview, confirmation link, merchant-only completion) come before any caveat. One of four sentences is dead weight — the money-units sentence is irrelevant to a tool with no monetary parameters — so it is not flawless.

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?

There is no output schema, so the description carries the burden of describing the return, and it does the essential part: it tells the agent the response is a preview plus a confirmation link and that the mutation happens out of band. It does not describe what the preview payload contains, which is a modest remaining gap.

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%, and the schema itself fully documents URLs, null semantics, pixel ranges, and aspect-ratio behavior, so the baseline is 3. The description adds no parameter meaning at all — its only parameter-adjacent sentence, "Money is integer minor units (cents)," refers to no parameter in this schema and is a stray from another tool's template.

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 opening sentence names a specific verb and two distinct resources: "Set the shop's logo and the one its emails carry." An agent can immediately tell this is the branding/logo tool rather than a theme, identity, or content tool, and the storefront-vs-email distinction is stated up front.

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 clearly explains the calling context: invoking it produces a preview of what would change plus a confirmation link, and only the merchant on that page can complete the change. That is strong when-to-use context, but no alternative tool or condition for choosing a different path is named.

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