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

Annotations already declare readOnly, idempotent and openWorld, so safety is covered. The description adds genuinely new behavioral context the annotations cannot convey: the call is paid ($0.02 USDC per call via x402 on Base or Solana) and the upstream source is CoinGecko. It stops short of disclosing rate limits, freshness/latency, or failure behavior for unsupported symbols.

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?

Three sentences, front-loaded with the return payload before source and payment details. Slightly wasteful because the 20-symbol list restates the schema enum verbatim, but the overall length is proportionate and no sentence is filler.

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?

There is no output schema, but the description compensates by enumerating the returned fields (price, 24h change, market cap, volume) and disclosing the payment model, which is essential before invoking a paid endpoint. Remaining gaps are minor: unsupported-symbol behavior and data freshness are unstated.

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 description coverage is 100% and the single 'coin' parameter is a fully enumerated string, so the schema carries the parameter semantics. The description's list of supported symbols duplicates the enum value-for-value rather than adding format or edge-case meaning, so baseline 3 applies.

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 ('Returns') plus the exact resource: current USD price, 24h % change, market cap and 24h volume for supported cryptocurrencies. It also names the data source (CoinGecko) and lists the supported symbol universe, so the agent knows precisely what data points come back and which coins qualify. The word 'current' implicitly separates it from the sibling get_crypto_history.

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 implies the usage context ('current' price) which implicitly contrasts with get_crypto_history, but it never states when to prefer this tool versus its siblings or when not to use it. There are no exclusions or prerequisites beyond the implicit supported-symbol constraint, which the schema already enforces.

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