Bitcoin-MCP

check_utxo

Verify if a Bitcoin transaction output is unspent by providing the transaction hash and output index.

Instructions

Check if a specific transaction output is unspent (UTXO lookup).

Args: txid: Transaction hash vout: Output index

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "txid": "<txid>",
      "vout": "<vout>"
    },
    "name": "check_utxo"
  }
}

Input Schema

Name	Required	Description	Default
`txid`	Yes
`vout`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.5.1Apr 2, 2026

TDQS

A3.5/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool checks if a transaction output is unspent, implying a read-only lookup, but doesn't disclose potential behaviors like error handling, rate limits, authentication needs, or what the output contains. For a tool with no annotation coverage, this is a significant gap in transparency.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is appropriately sized and front-loaded, with the core purpose stated first in a single sentence, followed by a brief parameter explanation. Every sentence earns its place without redundancy, making it efficient and easy to parse.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's low complexity (2 parameters) and the presence of an output schema (which handles return values), the description is somewhat complete but lacks behavioral context. Without annotations, it should ideally mention more about the tool's operation (e.g., read-only nature, potential errors) to fully compensate for missing structured data.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It adds clear meaning beyond the schema by explaining that 'txid' is a 'Transaction hash' and 'vout' is an 'Output index', which clarifies the semantics of these parameters. However, it doesn't provide format details (e.g., hex string for txid) or constraints, leaving some gaps.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose with a specific verb ('Check') and resource ('transaction output'), and distinguishes it from siblings by specifying 'UTXO lookup' rather than broader analysis or listing functions. It precisely defines what it does: verifying if a specific transaction output is unspent.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

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 like 'get_address_utxos' or 'get_utxo_set_info', nor does it mention prerequisites or context for usage. It lacks explicit when/when-not statements or named alternatives, leaving usage unclear relative to sibling tools.

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

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