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

With no annotations, the description must carry the behavioral load, and it does disclose the return payload (deposit address, chain, exact amount) plus the significant side effect that a newly created key is returned only once. It omits whether the order expires, whether calling twice creates duplicate orders, and any auth/rate-limit context, so a 3 is fitting.

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 followed by the return payload and the key-creation caveat. No filler, though the parenthetical '(returned once)' is dense enough that it could be slightly clearer.

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 4-parameter mutation tool with no annotations, no output schema, and low schema coverage, the description covers the essentials (what it creates, what it returns, the one-time key behavior). The undocumented promo parameter and missing lifecycle details (order expiry, duplicate-call behavior) leave real gaps.

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 25%: only 'pack' is described in the schema, and chain/promo/api_key are bare. The description compensates for api_key (omit it to mint a new key, returned once) and implies chain's role through the return value, but the 'promo' parameter remains completely unexplained in both places.

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 gives a specific verb and resource ('Create a stablecoin top-up order') and even names the return payload, so the operation is unambiguous. It does not explicitly contrast itself with the sibling tools claim_topup and verify_topup, which is the only thing keeping it from 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?

It supplies one real usage hint ('Omit api_key to create a new key'), which tells the agent how to trigger key provisioning. However, there is no guidance on when to use this versus claim_topup or verify_topup, nor on prerequisites such as authentication or when a created order expires.

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