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

Annotations already indicate non-read, non-destructive, open-world. Description adds that it returns a cart_id and emphasizes reuse. No contradictions. Could mention if previous carts are invalidated, but overall adequate.

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 focused sentences plus a critical note. Every sentence serves a purpose, front-loaded with core action and return value.

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?

For a simple creation tool with two parameters and an output schema, the description fully covers what it does, when to use it, and an important reuse constraint.

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 schema already fully describes both parameters. Description adds no additional parameter meaning beyond the 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?

Description clearly states 'Create a new shopping cart for a specific site. Returns a cart_id.' The verb and resource are specific, and it distinguishes from sibling tools like get_cart or get_active_cart.

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?

Explicitly instructs when and when not to use the tool: 'Reuse the active cart_id across multiple products... Do NOT call create_cart again if you already have a cart_id.' This provides clear context and alternatives.

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