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

With no annotations, the description carries the full burden. It conveys determinism, citation of primary sources, and a non-billing policy for errors or unverified rules. It also mentions a per-call cost. This adds valuable behavioral context beyond the schema, though it does not address potential side effects or data mutations (it appears to be a read/calculation tool).

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 brief and front-loads the purpose, but it condenses multiple capabilities into a single run-on sentence. Pricing and determinism are mixed in without clear separation. It is not overly verbose, but structure could be improved with clear sections or bullet-like phrasing.

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 7 parameters, high complexity (nested objects), no output schema, and low schema coverage, the description is insufficient. It provides a high-level overview but omits critical details like mode values, line input structure, as_of format, and return expectations. An agent would struggle to invoke it correctly without additional documentation.

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 14% (only x_payment is described). The description does not explain any of the seven parameters (mode, as_of, lines, etc.) nor map features to inputs. It fails to compensate for the low schema coverage, leaving the agent guessing about parameter meanings.

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 indicates this tool deals with Japanese consumption tax, listing specific features like invoice rounding and qualified-invoice validation. It distinguishes from sibling tools (jp_bonus_net, jp_payroll_net, etc.) by focusing solely on consumption tax. It does not explicitly state 'calculate' or 'compute', but the intent is evident.

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?

There is no explicit guidance on when to use this tool versus alternatives. It does not mention prerequisites, exclusions, or when not to use it. The description simply lists features without contextual usage instructions.

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