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

Annotations already cover safety (readOnlyHint, openWorldHint), and the description adds genuinely useful context beyond them: a per-call charge of $0.003 USDC via the x402 payment scheme. It still omits pagination behavior, address-format support, and any rate limits, so it is not fully complete.

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 purpose and the return payload, followed by the cost constraint. Every clause carries information; nothing is restated from the name or annotations.

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 does the work of describing return values well, which is the main completeness burden here. The remaining gaps are the undocumented `limit` parameter and the absence of any alternative-routing guidance.

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 0% and the description compensates only for `address` (implicitly, by naming it as the lookup subject). The `limit` parameter is never explained, so an agent cannot tell that it caps how many transactions are returned.

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?

Opens with a specific verb+resource ("Bitcoin address lookup") and then enumerates exactly what is returned: balances in BTC and USD, totals received/sent, tx count, latest transactions. An agent can distinguish this from btc_tx or btc_fees from the description alone, though siblings are never named explicitly.

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?

There is no when-to-use guidance and no routing against alternatives such as btc_tx (single transaction lookup) or wallet. The only contextual remark is pricing, which tells the agent nothing about when this tool is the right choice.

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