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

No annotations are provided, so the description carries the full burden. It does add real behavioral value by disclosing the x402 payment model (0.01 USDC on Base, pay-per-use), which an agent needs before invoking. However it says nothing about data granularity, rate limits, or what the historical series 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?

Two compact sentences plus a bracketed cost tag; the purpose and the input format are front-loaded with zero filler. Nothing is wasted.

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 single-parameter tool with no output schema, the definition covers purpose, input encoding, and cost. Only the shape of the returned series (frequency, units, range) is left unspecified, a minor gap given the tool's simplicity.

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?

The schema is nominally 100% covered but the only description is the useless 'service input'. The tool description compensates fully by decoding the composite parameter: 'input=btc,7' (moneda,dias), telling the agent the string is coin,days. Without this the parameter would be unusable.

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?

'Historial de precios de una cripto' states a specific resource (price history) and scope (a crypto), which distinguishes it from the current-price siblings like precio-cripto and crypto-price. It stops short of explicitly naming those alternatives, so an agent must infer the current-vs-history distinction from the word 'historial'.

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 input example 'btc,7' implies how to call the tool, but there is no statement of when to use this versus precio-cripto, calcular-volatilidad, or correlaciones, and no exclusions or prerequisites. Guidance is purely implicit.

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