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

Annotations cover the safety profile (readOnly, idempotent, closed-world), and the description adds the crucial non-obvious behavior: this is a paid call, priced at 10 sats or US$0.01 USDC, with two settlement paths. It also discloses the result cap of 50, ordering, and the returned field set. It stops short of describing failure modes (unpaid call response, empty-window behavior), so it is not a 5.

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 definition, then the return shape, then price — a sensible order with no filler. The parenthetical field list is dense but earns its place given there is no output schema; the only minor cost is that it reads as one long sentence.

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 no-required-parameter, read-only feed with no output schema, the description covers scope, limit, ordering, returned fields, window totals, and payment terms — enough to call it correctly. Missing only edge-case behavior such as an empty window or what an unpaid invocation returns.

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 coverage is 100%, so the baseline is 3; however, the description supplies the payment price that explains why and when the l402 and pay_with parameters matter, which is meaning the schema does not convey. The '<token>:<preimage>' flow and enum choices themselves are already documented in the schema.

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 with explicit thresholds and scope: 'Bitcoin transactions of US$100,000 or more this node saw in the last 10 minutes', plus result cap and ordering ('up to 50, largest first'). This clearly separates it from siblings like bitcoin_aml_live (scoring) and whale_geopolitics_report (analysis), which an agent can distinguish 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 implied by the live 10-minute window and whale threshold, but the description never says when to pick this over whale_geopolitics_report or bitcoin_aml_live, nor what happens when the window is empty. There is no explicit when-to-use or when-not-to-use guidance.

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