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

Annotations cover the safety profile (readOnlyHint, idempotentHint, openWorldHint), and the description adds substantive economics beyond them: one voucher, one settlement, one signed XDR-1 receipt covering the whole batch. That billing/settlement behavior is exactly the kind of context the agent cannot infer from annotations. It does not state failure semantics for a partially invalid batch, which keeps it from 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?

Dense single block with the throughput and one-payment points front-loaded; every clause carries information. The all-caps framing and marketing superlatives ('10x cheaper') are slightly stylistic overhead but do not obscure the meaning.

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?

An output schema exists so return values need not be described, and the description covers batch size, supported checks, and the one-payment model. Missing only edge-case behavior (what happens when some items fail validation in a batch), which is a minor gap for this tool.

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 description coverage is 100% and the enum already lists every supported validator, so the description's enumeration of IBAN/LEI/VAT/... duplicates structured data rather than extending it. Baseline 3 is appropriate; no syntax or constraint detail (e.g. per-item error behavior) is added.

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+resource: run up to 50 identifier checks in one batch call, enumerating the exact validator types supported. It is clearly distinguishable from the single-check siblings (iban_check, lei_check, etc.) by its batching scope.

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 a clear when-to-use context ('essential for autonomous batch invoice processing') and a cost rationale ('10x cheaper per item'), which implies the alternative is issuing many single-check calls. It never explicitly names the sibling single-check tools as the alternative for small jobs, so it stops short of full routing guidance.

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