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

No annotations are provided, so the description carries the full disclosure burden. It does add genuinely useful behavior that the schema cannot convey: the x402 payment model (0.005 USDC on Base, pay-per-use), which tells the agent each call costs money. It stops short of stating rate limits, latency, or what the response payload 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 compact line, front-loaded with the purpose, followed by the input examples and the payment note. Nothing is redundant, though the x402 bracket is dense and could be split for readability.

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 one-parameter tool with no output schema, the definition covers purpose, input format, and cost. It leaves the return shape unexplained, however: 'USD/COP' is ambiguous about whether both currencies are returned together or whether one must be selected, and no output schema exists to resolve it.

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 nominally 100%, but the schema's own description is the useless placeholder 'service input', so the description is the only source of real meaning. By giving accepted examples ('btc, eth, sol') it tells the agent the expected token-symbol format, which the schema fails to do.

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 ('Precio EN VIVO de una cripto') and pins down the quote currencies (USD/COP), so an agent immediately knows this returns a live crypto price. It does not, however, differentiate itself from near-siblings such as crypto-price, historial-precios, or fx, leaving the agent to infer the boundary.

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?

The word 'EN VIVO' weakly implies this is for live quotes rather than the historical series (historial-precios), but there is no explicit when-to-use, when-not-to-use, or named alternative. The only contextual hint is the pay-per-use cost note, which is a cost consideration rather than routing guidance.

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