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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered. The description adds genuinely non-obvious behavior: a per-call price of USD 0.003 paid via x402 USDC on Base, and that failed calls are not charged – material cost context an agent cannot get from structured fields.

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?

Two sentences, no filler, with the metric scope front-loaded before the cost caveat. Every sentence carries distinct information.

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 usefully enumerates what comes back and discloses payment mechanics, which is enough for a one-parameter read tool. Minor gaps remain around result shape (per-coin object structure) and whether the 15-minute window is fixed.

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 optional 'tokens' parameter is fully documented in the schema (comma-separated tickers, up to 50, empty means top 50). The description adds nothing about the parameter, which is acceptable at this coverage level but not above baseline.

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 names the exact resource and enumerates the specific metrics returned: bid-ask spread, order-book imbalance, buyer share over the last 15 minutes, and volume versus normal, all per coin. That is concrete enough to separate it from siblings like prices, whale_orders, and liquidations without opening any 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 only implied by the metric list – an agent can infer this is the tool for depth/flow analysis, but there is no explicit when-to-use, when-not-to-use, or named alternative (e.g. prices for simple quotes). The billing note tells the agent about cost, not about tool selection.

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