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

Annotations only declare readOnlyHint and openWorldHint, so this description carries the rest of the burden — and it does well: it names the backing model (Llama 3.3 70B), states that only the rewritten text is returned, flags that nuance can shift, caps input at 8,000 characters, and discloses the paid x402 model with per-success charging. The one omission is any mention of latency or failure modes beyond billing.

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?

Front-loaded with the core transformation, then layered with operational facts (variants, model, output, limit, caveat, price) — each sentence earns its place. The 8,000-character cap is duplicated in the text parameter schema, a minor redundancy that keeps it just under the top band.

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 an existing output schema, the description need not explain return values, yet it usefully confirms only the rewrite comes back. Combined with annotations, model disclosure, limits, and pricing, an agent has everything needed to invoke this correctly and safely.

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 the schema already documents all four parameters with their defaults and value sets. The description largely restates the tone and length enumerations rather than adding syntax or edge-case meaning, so the baseline 3 applies.

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 opens with a specific verb+resource ('Rewrite a text') and immediately scopes it with the two control axes (tone, length) and a meaning-preservation constraint. An agent can distinguish this from text_grammar, text_tone, or translate without opening schemas. It does not, however, explicitly name any sibling tool, so it misses the top band.

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 implied by the enumerated tones and lengths (e.g. use it to make text shorter or more formal), but there is no explicit when-to-use/when-not guidance and no routing to alternatives such as text_grammar for error correction or translate for language change. The 'read the result' caveat is a quality hint rather than usage guidance.

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