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

Annotations already cover the read-only/idempotent/no-destruction profile, and the description adds genuinely new behavior: per-document billing, "validated in memory and never stored or logged", and synthesized confidence/disclaimer fields. The long response enumeration partly duplicates the existing output schema, which slightly dilutes the value.

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?

Purpose, use case, cost, and data-handling are front-loaded, which is right. But the third sentence is a lengthy field-by-field response listing that repeats the output schema rather than adding interpretation, so a chunk of the text does not earn its place.

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?

Return values and data-retention behavior are well covered (and the output schema exists anyway), but for a 4-parameter batch validation tool the total silence on preflight and jurisdiction leaves an agent guessing on two of four inputs, one of which is an opaque enum.

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 only 50% and the two undocumented parameters, preflight (boolean, default true) and jurisdiction (auto|ae|ae-sb|sa), are never mentioned in the description. The description covers the output side and the html format, but says nothing about what preflight=false disables or how the jurisdiction enum should be chosen.

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?

"Batch preflight" plus "per-document verdicts, readiness percentage" gives a specific verb (validate in batch) and resource (e-invoices) and implicitly distinguishes itself from the single-document sibling validate_invoice, though it never names it. An agent can tell what it does without opening the 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?

"For a go-live check or an ERP regression suite" supplies clear when-to-use context, and the batch framing plus "Charged per document" signals scale/cost tradeoffs. It stops short of naming validate_invoice as the single-document alternative or stating when not to use it.

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