check_utxo

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

No annotations are provided, so the description carries the full burden. It only states the tool performs a lookup/check but doesn't describe the return format (boolean vs UTXO details), what constitutes 'unspent' versus 'spent', or error cases (e.g., if the transaction doesn't exist). With zero annotation coverage, this lacks necessary behavioral context.

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 appropriately brief with no wasted words. The structure separates the purpose statement from parameter definitions using an 'Args:' section. While functional, the docstring-style formatting is slightly less polished than natural language integration, preventing a perfect score.

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 2-parameter lookup tool with an existing output schema (per context signals), the description provides sufficient context. The Args section compensates for the schema's lack of descriptions, and the output schema presumably handles return value documentation, making this complete enough for the complexity level.

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?

With 0% schema description coverage (neither txid nor vout have schema descriptions), the description compensates by providing 'Transaction hash' and 'Output index' semantics in the Args section. This adds essential meaning missing from the structured schema, though it could further clarify format expectations (e.g., hex string for txid, 0-indexed integer for vout).

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 checks if a specific transaction output is unspent, using the specific verb 'Check' and resource 'transaction output/UTXO'. It implies specificity by mentioning 'specific transaction output' (txid+vout), distinguishing from address-based queries like sibling get_address_utxos, though it doesn't explicitly name that alternative.

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 no guidance on when to use this tool versus alternatives. It fails to mention that get_address_utxos is preferred when querying by address, while this tool is for checking specific outpoints. No prerequisites, error conditions, or usage constraints are mentioned.

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