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

Annotations already flag destructive=true and openWorld=true, so the safety profile is partly covered. The description adds genuinely non-obvious behavior: the fixed execution order, that `update` avoids re-quoting while `add` is quoted, and that the full cart is returned — context the annotations cannot express.

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 dense sentences with zero filler; the ordering constraint and the return-then-don't-call-get_cart rule are both front-loaded where an agent will read them.

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 multi-param mutating tool with no output schema, the description covers execution order, quoting behavior, and the return value shape, plus the anti-pattern (don't call get_cart). It omits nothing critical, though it could note that cartId is a bearer capability.

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 earns a bump by explaining the operation ORDER of the `remove`/`update`/`add` parameters — semantic information a JSON schema cannot convey — plus the no-re-quote vs quoted distinction, though it does not restate cartId's capability warning.

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 (applies mutations) and resource (the cart), and uniquely conveys the atomic ordering semantics: remove → update → add. It implicitly differentiates from get_cart by telling the agent not to call it afterward, but does not explicitly contrast with create_cart/delete_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?

Gives concrete usage direction: apply operations in a fixed order, expect a fully-updated cart back, and do not follow with get_cart. It stops short of stating prerequisites (e.g., cart must exist / come from create_cart) or when to prefer delete_cart.

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