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

Annotations already declare the safe, non-destructive, closed-world profile, so the description's added value is the non-obvious payment behavior: a 402 with PAYMENT-REQUIRED, USDC settlement, and a re-send with a PAYMENT-SIGNATURE header. It also discloses delimiter detection and typed-column inference, which an agent cannot infer from the schema.

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 English portion is two tight, front-loaded sentences with no filler. The appended Japanese payment block is relevant and earns its place, but the mid-description language switch slightly hurts scannability.

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?

With no output schema, the description should ideally characterize the returned payload; it only implies that the converted data comes back. Everything else an agent needs, including the full 402/payment retry flow, is present and complete.

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%, so both parameters are already documented, and the enum on "to" is self-explanatory. The description only loosely reinforces this with "in either direction" and the note about inferred target format, adding little beyond the schema baseline.

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 gives a specific verb and resource: convert tabular data between CSV/TSV and a JSON array of objects, in either direction. That is unambiguous and clearly distinct from siblings like diff, regex, or the buy_* services, though it never explicitly names or contrasts a sibling tool.

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?

"Use it when a tool returns CSV but your pipeline needs JSON (or the reverse) and you do not want to run a parser yourself" gives a concrete triggering condition. It stops short of naming exclusions or alternative tools, and the payment precondition is stated as mechanics rather than as a when-to-use rule.

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