Update Account Cart Item

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

Annotations already disclose destructiveness, idempotency, open-world behavior, and non-read-only status. The description adds substantial context beyond those annotations: host approval is required, quantity increases obey both caps, and retries never resend mutations. This directly addresses safe retry and mutation-scope concerns.

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?

Three short sentences, front-loaded with the action and then the key constraints. Every sentence adds a distinct operational fact with no filler or repetition.

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?

The description covers high-stakes mutation behavior well: approval, caps, retry semantics. But with 0% schema coverage, it is incomplete on parameter meaning, especially session_token and plan_id format, and it does not relate this tool to the prepare/reconcile siblings in the account-cart workflow. Output schema existence means return values need not be described.

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 description coverage is 0%, so the description must carry parameter meaning. It adds some context for plan_id by calling it an 'approved update plan,' but it never explains session_token, plan_id format/pattern, or how the plan encodes the final quantity. The gap for a two-parameter mutation tool is significant.

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 (PATCH) and resource (final quantity via the account's approved update plan), making the action distinguishable from generic cart tools. It does not explicitly name a sibling tool or say how it differs from prepare_account_cart_change, keeping it short of a 5.

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 an explicit prerequisite: 'Requires explicit host approval' and implies use only with an approved update plan. However, it does not say when to choose this over siblings like prepare_account_cart_change, reconcile_account_cart_operation, or update_cart_item, nor does it state when not to use it.

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