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

No annotations exist, so the description carries the burden, and it does substantial work: it discloses the returned fields, the flat 0.01 XAH facilitator fee and second-payment mechanism, SML fee exemptions, and the XRPL third-party fee binding from first settlement. It omits auth requirements, idempotency, and whether invoking it creates persistent state, which keeps it short of a 5.

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 purpose and return shape, then parameter routing, then fee edge cases. The fee sentence is dense and parenthetical-heavy but every clause conveys a real behavioral fact, so little is wasted.

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 tool with no output schema and no annotations, the description covers return contents, per-chain routing, and fee exceptions, which is most of what an agent needs. Prerequisites such as authentication or whether the invoice expires are the main remaining gap.

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 already 100%, so the baseline is 3; the description earns extra by spelling out concrete parameter combinations per rail (currency+chain for Solana, asset or chain for Xahau) that go beyond the terse schema blurbs.

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 ('Request a payment invoice') plus the scope ('any SqueezeOS endpoint'), and immediately lists what it returns (destination address, amount, payment_options), which lets an agent distinguish it from settlement/verification siblings like verify_payment.

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 usage context through rail selection rules (currency='USDC' + chain='solana' for Solana; asset='XAH' or chain='xahau' for Xahau) and notes the call is free, but never explicitly states when to choose this over siblings such as verify_payment or merchant_pricing.

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