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

With no annotations, the description carries the full burden; it does disclose valuable traits a schema cannot: returns a signed JWT access_token with a 1-hour TTL, requires both on-chain payments for Xahau fee_required settlement, and is free. It says nothing about failure modes, idempotency, or whether the tx must be confirmed on-chain before submission, which are the behaviors that matter most for a settlement-verification call.

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?

Four short clauses, each with distinct payload: the action, the chain formats, the JWT return with TTL, the Xahau dual-payment caveat, and the cost. The main instruction is front-loaded and nothing is redundant.

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 6-parameter tool with no annotations and no output schema, the description does cover the return value (signed JWT, 1-hour TTL) and the tricky Xahau case. But the roles of agent_wallet and agent_domain, and the relationship the submitted tx_hash must have to the invoice, remain unexplained, leaving real gaps for a mutation-style settlement call.

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 50%: tx_hash, fee_tx_hash, and recovery_secret are already documented in the schema, and the description mostly restates those (format per chain, fee_required condition). The undocumented parameters invoice_id, agent_wallet, and agent_domain get no semantic explanation in the description, so the coverage gap is not compensated.

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 (submit tx_hash to verify payment for an invoice) plus the supported chains and the return artifact, so the action is unambiguous. It does not explicitly differentiate itself from siblings like get_invoice or get_compliance_receipt, leaving the agent to infer the invoice-then-verify sequence.

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?

"Submit tx_hash after paying an invoice" gives a clear precondition, and the Xahau branch ("with fee_required=true, also submit fee_tx_hash") is an explicit conditional instruction. There is no guidance on failure/retry paths, whether it can be re-called for an already-settled invoice, or which sibling to use instead for read-only invoice lookups.

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