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

Annotations indicate mutability (readOnlyHint=false) and the description clarifies it creates a cart and returns a working checkout link. However, it does not disclose potential side effects like cart persistence or cart lifetime, which would be helpful for complete transparency.

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 exceptionally concise at 4 sentences, front-loading the core purpose and then breaking down modes and exclusions. Every sentence adds non-redundant information, making it efficient for an AI agent to parse.

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?

Given the tool has no required parameters and no output schema, the description fills the gap by stating what is returned ('a widget with the cart items and a working checkout link'). It covers the primary behavior, but could mention edge cases like what happens if both modes are invoked or if no products are found.

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 input schema already provides good descriptions for all three parameters (100% coverage). The tool description adds value by explaining the two usage modes and how parameters interact (e.g., 'query' used only if 'products' not provided), which is not evident from the schema alone.

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 description starts with a clear verb-resource pair ('Create a buyable shopping cart') and specifies two distinct modes (products array vs query). It also explicitly distinguishes itself from sibling tools like search_products and skincare_recommend, making its purpose unambiguous.

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?

The description gives explicit when-to-use ('to create a cart with checkout URL') and when-not-to-use ('Do not use for browsing or recommendations'), along with clear alternative tools ('use search_products or skincare_recommend first'). This provides excellent guidance for an AI agent.

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