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

Annotations already cover safety (readOnly, idempotent, non-destructive). The description adds meaningful non-annotation context: the data source (mempool.space public API, keyless) and, importantly, a payment requirement of 0.01 USDC per call via x402 on Base. That cost disclosure is behaviorally valuable; only return/pagination details are absent.

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?

A single dense sentence, front-loaded with the resource and the tier names, with metadata (source, payment) trailing. Nothing is wasted, though the bracketed payment clause makes it slightly crowded.

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 keyless read-only fee lookup with no output schema, the description enumerates the returned fields (five fee tiers plus block height), which is what the agent needs. Source and cost are covered; only edge behavior (e.g. rate limits, error handling) is unstated.

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?

The single parameter has 100% schema description coverage but is documented only generically as 'product parameters (JSON or text)'. Per the high-coverage baseline, 3 is appropriate — the schema carries the load and the description adds no format or content guidance for the parameter.

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 resource and content: Bitcoin fee tiers in sat/vB (fastest/half-hour/hour/economy/minimum) plus block height. 'Bitcoin only' implicitly separates it from gas_oracle_multi, but no sibling is named explicitly. An agent can tell what it returns without opening the 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 resource description (get Bitcoin fee estimates) but there is no explicit when/when-not guidance or named alternative. 'Bitcoin only' mildly signals that multi-chain fee queries belong elsewhere, but this is left to inference.

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