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

Annotations already establish readOnlyHint=false, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds real behavioral context beyond that: product URLs are resolved to variant IDs automatically with no catalog import, and the return value is a clickable Shopify checkout link. It stops short of describing failure modes or what decision_id does (left to the schema), so a 4 rather than 5.

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?

Front-loaded with the core action in the first sentence, then progressively adds resolution behavior, supported features, the exclusion rule, and the return value. Every sentence carries distinct information; nothing is repeated from the schema.

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?

With no output schema, the description correctly names the return value (a direct Shopify checkout link) and covers input modes and usage boundaries. Minor gaps remain around error/retry behavior tied to decision_id, which is only hinted at in the 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 baseline is 3. The description adds the 'and/or' relationship between items and product_urls that the schema does not state (required params = 0), and surfaces the higher-level capabilities (discount codes, cart notes, selling plans) that map to individual params.

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 ('Create a checkout URL for one or more products') and goes further by explaining the two input modes (variant IDs vs product URLs) and the automatic URL-to-variant resolution. It is clearly distinguishable from siblings like search_products or shop.

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?

Contains an explicit exclusion with named alternatives: 'Do not use unless the user wants to buy — use search_products or skincare_recommend first.' This tells the agent both when not to call it and what to call instead, which is exactly the routing guidance siblings lack.

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