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

Goes well beyond the readOnlyHint/openWorldHint annotations: it discloses the credential-free data source, the server-side fixed URL, and the fallback chain (vanity domain -> discovered *.myshopify.com -> embedded page data) that changes what the caller may get back. This is exactly the kind of behavioral context annotations cannot carry.

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?

Dense but every sentence earns its place, and the core purpose is front-loaded. The fallback sentence is long but justified by the non-obvious behavior it documents.

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?

Output schema exists, so return-value explanation is unnecessary. Given zero params and a read-only wrapper, the description covers sourcing, constraints, fallbacks, and the sibling alternative — nothing an agent needs 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?

The schema has zero parameters (baseline 4). The description adds value by explaining the negative — why no url parameter exists — which heads off a likely agent error rather than just restating the empty schema.

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 ('Returns normalized storefront metadata for Rebag') and pins it with the exact storefront URL. It explicitly frames itself as the brand-pinned variant of the generic Shopify store family, so an agent can distinguish it from shopify_store without opening either schema.

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?

Makes the calling constraint explicit ('no `url` parameter is accepted') and routes the agent to rebag_page for static pages. It does not explicitly say 'prefer shopify_store only for other brands' but the brand-pinning framing makes the selection condition clear.

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