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

With no annotations, the description carries the full burden and does solid work: it discloses the paid cost ($0.01 USDC on Base or Solana), that no account or API key is needed, that failed calls are not charged, and the underlying endpoint URL. It omits rate limits and what a failure or response payload looks like, which keeps it from a 5.

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?

Five short sentences, front-loaded with 'Paid.' so the cost is unmissable before the agent commits. Pricing, auth, failure policy and endpoint each appear once with no redundant restatement of the tool name.

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 zero-param, annotation-free, no-output-schema tool, the description covers the commercial model, authentication, failure billing and the three returned data points, which is enough to call it safely. It stops short of describing the response shape or freshness guarantees, which would matter for a 'live' price.

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 tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. The description correctly implies no inputs are required and that the coin is baked into the tool itself.

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 resource and data set: 'The Interfold (FOLD) price: live USD price, 24h change and market-cap rank.' An agent knows exactly what data comes back. It does not differentiate itself from the many sibling families (buy_coin_*, buy_crypto_price, buy_polymarket) or explain why one would pick the tok_ variant, so it stops short of a 5.

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?

Usage is only implied by the resource name – fetch the FOLD price. There is no explicit statement of when to use this versus buy_crypto_price or the buy_coin_* equivalents, and no prerequisites or exclusions beyond the payment mechanics. The payment terms tell the agent what it costs, not when to choose it.

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