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

Annotations already cover safety (readOnly, non-destructive, closed-world), and the description adds the return shape (rendered image URL) plus the high-frequency scroll invocation pattern, which matters for batching or rate considerations. It stops short of any explicit cost or throttle guidance given that per-scroll calling pattern.

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?

Two short sentences, front-loaded with the caller context before the return value. The opening clause about the preview panel is slightly wordier than needed but earns its place by explaining the invocation cadence.

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?

An output schema exists and both parameters are fully documented in the schema, so the description needn't explain returns or inputs. The only residual gap is the fuzzy overlap with preview_page, but nothing required to call it correctly 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 100% and both parameters already document their provenance (index from preview_page, catalogId from list_catalogs). The description adds nothing about either parameter, so the 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 concrete verb+resource: returns one catalog page as a rendered image URL. It also names the sibling preview_page and positions this as the panel-driven image variant, though the distinction ('preview_page is the tool that shows pages to the merchant') is a bit circular for an agent that only knows it wants a page.

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 discloses the intended caller ('the preview panel, which calls it for each page as it scrolls into view') and points at preview_page as the merchant-facing alternative. The routing condition is implied rather than stated as an explicit 'use X when / use this when', so an agent has context without a crisp rule.

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