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

Annotations cover the safety profile (readOnly, openWorld, non-destructive), but the description adds substantial context they cannot: the cursor-based incremental-fetch model, what the first call returns, the per-call price, the payment rails (x402/USDC on Base, Solana, Polygon, Arbitrum), and how payment happens automatically.

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 behavior and output, then usage, then cost/payment. Every sentence is informative, though the x402/payment-method detail is verbose and slightly dilutes the core description.

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 carries the return-value burden and does so (direction, net BTC, confirmations, time, balance). It also covers cursor state, pricing, and a free-sample call, leaving nothing essential missing for correct invocation.

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 67%, so the schema documents address and cursor partially. The description adds real meaning for cursor ('pass it back next time'), clarifying the stateful loop contract beyond the schema's terse 'Cursor from the previous call'. limit remains unexplained, keeping it from a 5.

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 verb (watch) and resource (a Bitcoin address), and precisely describes the incremental output: only new transactions since the last call, with direction, net BTC, confirmations, time, and balance. This distinguishes it from one-shot siblings like btc_tx and btc_address.

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?

Gives concrete intended uses ('deposit detection and treasury or whale watching') and explains the loop/cursor workflow that selects it. It does not explicitly name an alternative or a when-not condition, so it falls just short of a 5.

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