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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=true. The description adds valuable non-obvious behavior: $0.02 per call, the x402 payment mechanism, the x-credit-token header for unlimited calls, a free daily call, and no wallet/API key requirement. These are precisely the kind of rate-limit and auth details that agents cannot infer from the schema or 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 dense but well-organized: function first, use case second, required input, then cost/auth constraints last. Every sentence carries distinct information; there is no repetition of schema details or annotation flags. It earns its length with operational detail.

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 rich annotations and an output schema, this description covers all an agent needs to invoke it correctly: what to pass, the limit, the response contents, the use case, and the cost/authentication model. No critical operational gap remains.

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%, so the baseline is 3. The description goes beyond the schema by adding the maximum batch size (up to 10) and specifying the chain is Base, which are critical constraints not present in the schema's parameter description. It also clarifies the expected output fields (USD price + 24h change).

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: get USD prices + 24h change for up to 10 Base tokens. The batch scope ("up to 10" and "in one call") clearly distinguishes it from sibling single-token pricing tools like token_price. No ambiguity about what is returned.

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?

Explicitly identifies the ideal scenario: "agents pricing a portfolio or watchlist." It does not name an alternative tool or state when not to use it, but the batch context is clear and sufficient for most routing decisions. Could be more explicit about single-token alternatives.

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