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

Annotations cover the read-only/open-world safety profile, and the description adds substantial operational context beyond them: cost of $0.002 USDC per successful call via x402 on Base/Solana/Arc, failed calls not charged, and that data refreshes on CoinGecko's own schedule. The row-level structure clarification (one exchange pair per row) also prevents a common misread of the output.

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?

Front-loaded with the core purpose and metrics, and every clause adds usable information. It is dense and slightly run-on, packing metrics, row semantics, source cadence and pricing into a few sentences, but nothing is redundant.

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?

With an output schema present, the description needn't explain return values, and it still covers the row granularity, data source, update cadence and payment/cost model. For a single-param read tool with rich annotations, an agent has everything needed to select and 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 description coverage is 100% with a single param that already documents the CoinGecko id format with examples (bitcoin, ethereum, solana). The description only restates 'for one coin' and adds no format or edge-case detail, 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?

States a specific verb+resource (CoinGecko per-exchange market depth for one coin) and enumerates the exact metrics returned: 2% up/down liquidity cost, 24h volume, last price, bid-ask spread over the 15 top-volume pairs. The explicit note that each row is one exchange pair, not a merged order book, cleanly separates it from order-book siblings like crypto_binance_orderbook_depth or crypto_hyperliquid_perps_depth.

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 implied by the metrics described (you'd use it to gauge per-exchange liquidity), but there is no explicit when-to-use/when-not guidance or named alternative among the many overlapping depth/price tools. The agent must infer selection from the data-source and granularity cues rather than being told.

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