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

Annotations already declare readOnlyHint and openWorldHint, so the safe read-only nature is covered. The description adds meaningful operational context beyond annotations by disclosing the $0.03 per-call cost paid in USDC on Base via x402. There is no contradiction with the annotations.

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 description is three short sentences with no filler. It front-loads the core scope, then clarifies tool selection, then adds the cost/payment detail. Every sentence earns its place.

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 simple read-only market overview with two optional, well-documented parameters, the description covers the main data groups and the payment context. It could be more explicit about the exact response shape or field names, but nothing essential is missing for an agent to invoke it correctly.

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%: both vs and limite have descriptions and defaults. The description reinforces the 'coins by market cap' output that limite controls, but it does not add meaning beyond what the schema already provides, so the baseline 3 is appropriate.

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 states exactly what the tool returns: total market cap, Bitcoin dominance, 24h change, coins by market cap, and top movers. It also explicitly frames this as the 'context question' rather than a single-asset query, which distinguishes it from siblings like precio and ficha_token.

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 description gives clear usage context: use it for a broad market overview, and explicitly says it is not for questions about a single asset. It does not name alternatives directly or list when not to use it, so it falls just short of full routing guidance.

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