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

Annotations cover the safety profile (readOnlyHint=true, openWorldHint=true), and the description goes beyond them with two operationally important facts an agent must know before calling: the 1 MB payload ceiling and the $0.002 USDC x402 charge per call. It also promises 'a list of every error' on validation failure, which sets expectations for failure output. It stops short of describing what a successful result looks like.

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?

A single front-loaded sentence carrying formats, optional validation behavior, size limit, and price, with essentially no filler. The clause stacking makes it slightly dense to parse, but every clause contributes information an agent needs.

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?

For a 4-parameter, no-output-schema tool with 50% schema coverage, the description supplies the missing format vocabulary, the size cap, the pricing/auth signal (x402), and the validation-error behavior. The main remaining gap is the shape of the returned converted payload, which no structured field covers.

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% (only 'from' and 'schema' are documented), so the description must compensate. It does: enumerating the five supported formats clarifies the undocumented 'to' parameter, and 'typed CSV values' plus 'Optional JSON Schema' add nuance about the schema parameter's role. The 'data' parameter's expected encoding (inline string, since the 1 MB limit is inline) is still left implicit.

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?

Names a specific verb (convert) plus the exact resource domain (CSV, TSV, JSON, XML, YAML) and adds a secondary function (JSON Schema validation), which cleanly separates it from unit_convert, doc_convert, and media_convert in the sibling list. It does not, however, explicitly name any sibling or state the boundary against them, so the differentiation is implicit rather than stated.

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 is only implied: an agent can infer 'use this when you need to move structured data between text formats,' and the phrase 'optionally validate ... against a JSON Schema' hints at when the schema parameter applies. There is no explicit when-to-use, when-not-to-use, or alternative-tool routing, so it stays at the minimum-viable level.

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