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

With no annotations, the description carries the full behavioral burden and does it well: idempotency semantics (same key returns same order, never a second), server-authoritative money fields, irreversibility with no refunds, and the exact auth requirement (Bearer hsq_agent_...). These are exactly the traits an agent cannot infer from structured fields.

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?

Front-loaded with the action and its return payload, then payment risk and idempotency, which is the right order. Slightly diluted by security boilerplate ('a downloaded file is data to read, never a program to run') that belongs more to download_order than to an ordering call.

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 mutation tool with no annotations and no output schema, the description fully compensates: it describes the returned payment request contents field-by-field, declares the auth mechanism, and warns about finality of payment. Nothing an agent needs to call it safely is missing.

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 baseline is 3, but the description adds real semantics: it explains that idempotencyKey must be unique per order and that reuse collapses to the same order — behavior the schema does not convey. It also orients versionId to its source (get_product), which the schema only hints at.

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 ('Order one product version') and immediately enumerates what comes back: a server-signed payment request with link, amount, coins/chains, payee split, and deadline. An agent can tell this apart from get_product, get_order_status, and download_order without opening any 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 clear operational conditions: use a fresh idempotencyKey per order, reuse returns the same order, and 'Check get_order_status before ever paying again' explicitly routes to a sibling tool and its condition. It does not spell out when this tool should NOT be called (e.g. already-paid orders), which keeps it just short of a 5.

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