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

Annotations already cover the read-only and open-world profile, so the bar is lower. The description adds meaningful behavioral context beyond them: the per-call x402 cost of $0.002 USDC and the fact that quotes are 'live...right now' (freshness). It does not mention rate limits or failure modes, but the cost disclosure is real added value.

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?

One sentence, front-loaded with the core identity before drilling into returned metrics and cost. Every clause carries information; nothing is redundant padding.

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 no output schema, the description appropriately enumerates the return contents, so return values are covered. But for a 2-parameter tool with 0% schema coverage, the total absence of any guidance on 'pair' format and the entirely unmentioned 'depth' parameter leaves a real gap an agent must guess at.

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 0% and the description does not compensate. It implies a 'pair' parameter exists but never states the expected format (e.g., BTC-USD), and 'depth' — the second parameter — is never referenced at all, leaving its units or meaning unexplained in both schema and prose.

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?

The description gives a specific verb+resource ('Live Coinbase order book for a pair') and then enumerates exactly what the response contains (best bid/ask, spread in bps, USD depth within 1%, imbalance, slippage tiers). This clearly distinguishes it from siblings like crypto_price or crypto_candles without the agent needing to open a schema.

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 content (real-time depth/slippage analysis) and the cost note ('$0.002 USDC per call') gives a practical reason to weigh it against free alternatives. However, there is no explicit when-to-use guidance and no named alternative (e.g., crypto_price, swap_quote) for an agent deciding between market-data siblings.

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