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

Annotations already declare non-read-only, idempotent, non-destructive, but the description adds the crucial behavioral facts the annotations cannot convey: nothing is charged by this call, payment happens on the returned URL, and repeating with the same idempotency_key and quote returns the same order. These directly shape how an agent should sequence and retry.

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 tight sentences, front-loaded with what the tool does, followed by the safety fact (nothing charged) and the idempotency contract. No filler.

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 no output schema, the description still tells the agent what comes back (payment URL and order_token), that no charge occurs, and how retries behave, which is everything needed to call and handle this tool correctly.

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 71%, so the schema documents most parameters, yet the description adds real meaning: the two required booleans must be true only after the buyer consented, tying them to a legal/consent condition rather than a mere flag. It does not add format detail for quote or idempotency_key beyond what the schema already states.

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 and resource (creates an order) plus what it produces (payment URL with tax handled, secret order_token). It also names the prerequisite artifact ('from a valid quote'), which distinguishes it from the sibling get_quote that produces that quote.

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 clear preconditions: a valid quote must exist and both consent flags must be true only after the buyer agreed. It also explains the retry path via idempotency_key. It stops short of explicit exclusions or naming the sibling to use instead when no quote exists, so it falls just short of 5.

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