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

Annotations already declare readOnlyHint and openWorldHint. The description adds useful context: it returns both confirmed and unconfirmed balances, and the unit is satoshis. This goes beyond the structured annotations and clarifies the tool's output.

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 a single, focused sentence. It starts with the action and includes the network, balance type, and return unit with no wasteful words.

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 simple get-balance tool, the description covers the essential aspects: network, balance types, and return unit. With annotations for read-only and open world, and a well-documented single parameter, no additional context is necessary.

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 100% for the single 'address' parameter, which already lists accepted types (P2PKH, P2SH, etc.). The description provides no additional parameter semantics, fitting the baseline of 3 for complete schema coverage.

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 function: get confirmed and unconfirmed balance for a Bitcoin address on Bitcoin testnet3. It uses specific verbs and resource, and the mention of testnet3 distinguishes it from mainnet siblings like btc_get_balance.

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 provides clear context by specifying 'Bitcoin testnet3', implying use for testnet addresses. It does not explicitly list exclusions or alternatives, but the network context is sufficient for a simple get-balance tool.

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