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

Annotations already declare readOnlyHint, destructiveHint=false and idempotentHint=false, but the description adds real context the annotations cannot: the $0.003/call price, payment paths (x402 USDC or card key), that failed calls are free, and the practical consequence that repeats are not free. It does not cover rate limits or output format, so it is not fully rich.

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?

Purpose is front-loaded, followed by use cases, example, pricing and a safety note in a tight block. It is dense but every clause carries information; only the style list is a mild restatement of the schema.

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?

Covers purpose, usage, cost and side-effect profile for a simple two-parameter tool. The main omission is that no output schema exists and the description never says what is returned (presumably the rewritten string), leaving the return contract implicit.

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 100% and the style enum is fully documented, so the schema carries the load. The description still adds value by restating the style options and supplying a realistic text/style example that clarifies the expected input shape, slightly above the baseline-3 case.

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?

States a specific verb+resource (rewrite text) and enumerates the exact style axes it operates on. The clause 'keeping the meaning and language' cleanly separates it from siblings like ai_translate and ai_summarize_text, which an agent can act on without opening either schema.

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 to polish emails, replies, product copy and messages' plus a concrete worked example gives clear when-to-use context. It stops short of explicit exclusions or naming alternatives (e.g. use ai_translate for a different language, ai_summarize_text for a digest), so routing is inferred rather than stated.

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