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

The description discloses a behavioral nuance: that ultra-active addresses may return degraded responses under index load newsletter, which is helpful. However, with no annotations provided, the description carries the full burden of behavioral disclosure. It does not mention any safety or read-only hints, but the nature of the tool implies a read-only operation, and the absence of annotations is compensated by the detailed functional description.

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?

The description is concise and well-structured: it front-loads the core output (balance, activity), then lists supported address types, and ends with usage guidelines and a note. Every sentence serves a purpose, providing valuable details without unnecessary verbosity.

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?

The description is complete for a single-parameter query tool. It covers the output fields, address formats, and usage guidance. Since there is no output schema, the description adequately explains what the agent can expect. The only minor gap is the lack of explicit mention of error conditions or rate limits, but overall it is sufficiently comprehensive for correct use.

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 address parameter in the schema is minimally described as 'Bitcoin mainnet address', but the description enriches it by listing supported address types (P2PKH, P2SH, bech32, bech32m). Since schema coverage is 100% for the parameter's existence, the description adds value by clarifying the expected format, which is not fully covered 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?

The description clearly states the tool's purpose: it provides balance and activity information for a Bitcoin address, listing specific data points like confirmed/unconfirmed balance, UTXO count, and transaction count. It distinguishes itself from sibling tools by focusing on address-specific data, whereas siblings like btc_block_summary and btc_tx_lookup cover blocks and transactions.

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 includes a 'When to use' section that explains the scenarios for using this tool, such as checking balance, fund receipt, or activity level. It does not explicitly mention alternatives or when not to use it, but for a single-address summary tool, the usage context is clear and sufficient.

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