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

With no annotations, the description carries the full behavioral burden. It usefully discloses the failure mode for missing/non-numeric inputs and hints at a payment model ('5 free trial calls per signed wallet'), but it does not state what happens after the free trial, whether a signed wallet or payment header is required, or what the response 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?

The core definition is a single tight sentence with the formula front-loaded. The trailing free-trial promo is padding but brief, and it does convey access-model context.

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 arithmetic tool with no output schema, the definition covers the computation and input validation, but it omits the return type/format (numeric value? string? rounding) and access requirements. Low complexity keeps this adequate but not thorough.

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%, so the description must compensate. It does map both parameters semantically (shares and price, multiplied together) and clarifies that both must be numeric despite being typed as strings. It adds no precision/rounding or format guidance, so the compensation is partial.

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 names a specific verb (computes) and resource (market capitalization) and even gives the formula 'shares multiplied by price', so an agent knows exactly what the tool does. It does not, however, explicitly distinguish itself from similarly named siblings such as x402-market-overview or x402-market-pulse, which are analysis tools rather than a simple multiplication utility.

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 guidance on when to use this tool versus alternatives like x402-enterprise-value or the other x402-market-* siblings. The only conditional statement ('a missing or non-numeric either input raises a bad request error') describes an error path, not a usage context.

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