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

The description discloses that prices are re-verified server-side and agent-supplied prices are ignored, which is critical behavioral information. It also notes the auth requirement and that it returns a payment_url. Since there are no annotations, the description carries the full burden and does so effectively.

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?

The description is two sentences, efficient and structured. It front-loads the legacy warning and directs users to the alternative before describing the tool itself, with no redundancy.

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 is complete for this tool's purpose: it explains why to use it, what it returns, and the key behavioral twist. The absence of an output schema is compensated by naming the return type. It fits well within the sibling ecosystem.

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 adds a crucial caveat about price fields being ignored, which directly impacts how the agent should populate those parameters. This elevates the usefulness beyond the schema, so a 4 is warranted.

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 description clearly identifies create_order as a legacy, auth-required tool that creates an order and returns a payment URL. It distinguishes itself from the UCP flow by being a single-call alternative, making its purpose and scope explicit.

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?

It explicitly states when to use this tool ('only if you hold a Bearer token and want a single-call path') and when to prefer the alternative (the UCP flow). This gives the agent clear decision criteria, including the credential requirement.

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