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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description adds context by detailing the exact output fields (rune name, amount, UTXO reference) and the intended operational context (before sending/splitting). There is no contradiction with annotations, and the additional details go beyond what the annotations provide.

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 two sentences with no fluff. The first sentence states the primary action and result, and the second sentence adds a concise use case. Every word earns its place.

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 one-parameter list tool with no output schema, the description covers the core behavior, output contents, and use case. It does not address edge cases like empty results or invalid addresses, but given the simplicity and strong annotations, the description is nearly complete. The lack of explicit alternatives is a minor gap given the sibling context.

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% — the bitcoinAddress parameter is fully described in the schema. The description only mentions 'on a Bitcoin address' without adding extra meaning or format details beyond what the schema already provides, so the baseline 3 is appropriate.

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 opens with a specific verb and resource: 'List the unspent transaction outputs (UTXOs) on a Bitcoin address that hold Rune tokens.' It clearly distinguishes from sibling tools like getRuneBalances by emphasizing individual rune-bearing UTXOs and specifying the returned fields (rune name, amount, UTXO reference).

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 a clear use case: 'Useful for inspecting a wallet's individual rune-bearing UTXOs before sending or splitting them.' It implies when this tool is appropriate but does not explicitly name alternative tools or state when not to use it, 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.