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

With no annotations provided, the description carries the full burden and does disclose a genuinely non-obvious behavioral trait: the call costs $0.001 USDC on Base via x402, which an agent must know before invoking. It also lists the response fields since no output schema exists. It still omits ordering of trades, the meaning of 'recent', rate limits and error behavior.

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 tight sentences with zero filler: what it does and returns, when to use it, then the cost. The purpose is front-loaded and the payment warning is not buried.

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 output schema, the description compensates by naming the returned fields and disclosing the x402 payment requirement. The remaining gap is the unspecified recency window and trade ordering, which matters for tape-style consumption.

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%: product_id carries the pattern and examples (BTC-USD, ETH-USD), and limit documents its default of 50 plus min/max. The description adds nothing beyond this, so the baseline of 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 (Fetch) and resource (recent crypto trades from Coinbase Exchange) scoped to a trading pair, and enumerates the returned fields. This clearly separates it from siblings like crypto-candles, crypto-top-of-book and crypto-price without needing their schemas.

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?

Gives concrete usage contexts (tape analysis, market monitoring, trading-agent context), which is better than generic guidance. However, it never names an alternative sibling or an exclusion (e.g., 'use crypto-candles for aggregated OHLCV instead'), so the routing decision is left partly to inference.

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