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

With no annotations, the description carries the full burden. It discloses the return type and a free-trial quota, but says nothing about authentication requirements beyond a 'signed wallet' hint, rate limits after the trial, pagination, error behavior, or whether the call is a pure read.

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 tight sentence plus a short pricing note; the core capability is front-loaded and nothing is padded. The emoji pricing tag is slightly noisy but brief.

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 two-parameter tool with 0% schema coverage, no annotations, and no output schema, the description leaves too much unspecified: which of `text`/`input` is the real input, whether either is required, and what the caller gets back on error. The return-shape sentence is the one piece of genuinely useful information.

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 0% and there are two ambiguous, seemingly redundant parameters (`text` and `input`) with no required flags. The description says only 'the supplied text', which does not tell the agent which parameter to populate or whether both are allowed, leaving the key ambiguity unresolved.

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 and resource ('Returns the Unicode code point of each character in the supplied text') and even gives the return shape ('array of integers'). It does not, however, differentiate itself from close siblings such as x402-char-codes or x402-to-unicode, which an agent would have to inspect separately.

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 when-to-use or when-not-to-use guidance, and no routing to alternatives like x402-char-codes or x402-to-unicode. The only contextual sentence is a billing note ('5 free trial calls per signed wallet'), which is not selection guidance.

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