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

No annotations are provided, so the description carries the burden. It discloses the cost ($0.015/call), specific checks, and that it accesses the official Japan NTA registry (an external call). It does not mention failure modes or data storage, but it provides substantial behavioral context beyond the tool name.

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?

The description is two sentences: the first front-loads the purpose and scope, the second states cost. Every word earns its place, with no fluff or redundancy.

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?

Given the absence of an output schema and annotations, the description provides a reasonable overview (output as accounting-ready JSON, cost, verification types) but lacks details on error handling, payment flow, and the required format of nested parameters. It is adequate for tool selection but not fully complete for invocation.

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 only 33% (only x_payment has a description). The tool description mentions 'line-item totals' and 'arithmetic consistency', hinting at the use of line_items and fields, but it fails to define the expected structure of the 'fields' object or the 'line_items' array. This leaves agents with insufficient information to correctly populate those parameters.

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 clearly states a specific verb ('Verify') and resource ('extracted invoice fields') and details multiple verification aspects (arithmetic consistency, line-item totals, JP registration check-digit, corporate-number existence). This distinguishes it from sibling document-processing tools like parse_document or structured_extract.

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?

Usage context is implied: use it when you have extracted invoice fields and need verification. However, there is no explicit guidance on when to use this tool vs alternatives, nor any exclusions or mention of alternative tools like parse_document or structured_extract.

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