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

With no annotations, the description carries the full burden and does disclose real behavior: a 60-second cache and, notably, that the tool is a paid x402 call at $0.002/call via USDC on eip155:8453. Rate limits, error behavior, and response shape remain unstated, keeping it short of 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?

Effectively one dense sentence stating capability and inputs, followed by cache and price metadata. Front-loaded and waste-free, though the payment clause is slightly cryptic in phrasing.

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 two-parameter read tool with no annotations and no output schema, the description supplies what an agent needs: source, returned fields, accepted inputs, caching, and cost. Only the exact response structure and failure modes are left implicit.

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 baseline is 3, but the description adds genuine meaning by clarifying that 'ids' accepts either CoinGecko ids or common tickers (btc, eth, sol) and that the quote currencies are the four USD/EUR/GBP/JPY options. That goes beyond the terse schema strings.

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+resource (live crypto prices), the data source (CoinGecko public API), the exact payload (price in USD/EUR/GBP/JPY plus 24h change), and the accepted input forms (id or ticker). This clearly separates it from fiat-oriented siblings like live_exchange_rates.

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?

It implies when to use it ('live cryptocurrency prices', ticker examples) and notes a 60s cache, but never names an alternative or states when another tool (e.g. live_exchange_rates) should be preferred. Usage is inferable but not explicit.

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