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

Annotations only declare readOnly=false, idempotent=false, openWorld=false; the description adds genuinely new behavioral facts: a per-call price (1000 sats / US$1 USDC), a 30-day lifetime, the delivery channels, and that feed links are returned. It stops short of explaining the payment handshake order (invoice then l402 token re-call) or what happens to an existing watch after 30 days.

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, front-loaded with the core behavior and closing with the commercial constraint; every clause carries information (duration, trigger, channels, return value, cost) with no filler.

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 correctly states the return value (feed links), and the schema supplies the payment-mode parameters. The only remaining gap is the sequencing of the paid flow (call, receive invoice, pay, retry with l402), which an agent must infer.

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 every parameter including the l402 token format and the x402/lightning enum is already documented in the schema; the description adds only the price context, which is not parameter-level detail. Baseline 3 is appropriate when the schema does the heavy lifting.

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 precise verb and resource (alerts/watch on a Bitcoin address) plus scope (30 days, every confirmed transaction paying to or spending from it), which is unmistakably distinct from the risk-scoring sibling bitcoin_address_risk. An agent can identify the operation 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?

The description conveys what triggers the alert and for how long, so the use case is implied, but it never says when to choose this over siblings or when not to use it, and no prerequisite conditions are stated beyond the price.

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