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

Annotations already declare destructiveHint=true and idempotentHint=true, so the mutation profile is known. The description adds value annotations cannot: the re-pricing side effect, the provenance constraint on quote-priced lines, and the interactive sign-in fallback of the connection. It does not explain what re-pricing means operationally or whether omitted options are preserved or reset.

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 purpose, then the constraint, then the auth behavior. No filler and nothing buried.

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 an output schema present, return values need no explanation, and annotations cover safety. For a destructive nested-configuration mutation the description supplies the key constraints, but leaves open how to clear an existing option (e.g., reset finishing) — a real gap given finishingIds 'replace' semantics.

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 100%, so every nested option field is already documented in the schema, including the 'only the options that change' note. The description's partial-update summary ('only what is given: a new quantity, stock, finish or size') largely restates that, so baseline 3 is appropriate.

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 first sentence names a specific verb and resource ('Changes one cart line's options') and states the side effect ('re-prices it with the pricing engine'), which cleanly separates it from add_to_cart, remove_cart_line and price_job. An agent can identify the operation without opening the schema.

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 a concrete exclusion ('A line from a quote Printdash priced cannot be changed') and states the prerequisite ('Needs a signed-in Printdash account'), plus what happens when it is missing. It does not name a sibling alternative for the excluded case, so not a full 5.

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