rune_utxos_by_address

THE RISK

Low Risk

Why rune_utxos_by_address needs a policy

This tool queries the Bitcoin blockchain to list unspent transaction outputs (UTxOs) containing runes for a given address. It has no side effects, cannot execute commands, modify data, delete data, or move funds. It is purely informational and read-only, consistent with other blockchain explorers. The blast radius of misuse is minimal—an attacker could only enumerate rune holdings, not steal or manipulate them.

From the tool's definition Tool description states 'Return all UTxOs controlled by the specified address' — it retrieves blockchain data with no modification or execution capability.

Documented attack patterns abuse exactly the kind of access rune_utxos_by_address gives an agent:

POLICY

How to control rune_utxos_by_address

PolicyLayer is an MCP gateway — it sits between your AI agents and Maestro MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for rune_utxos_by_address:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "rune_utxos_by_address": {}
  }
}

rune_utxos_by_address is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Maestro MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

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EXPLORE

Related tools and policies

More Maestro MCP Server tools

Destructive EventManagerService_DeleteTrigger Remove a trigger Deletes a specific trigger identified by its unique \ Execute esplora_broadcast_transaction Broadcast a raw transaction to the network. The transaction should be provided as hex in t Execute rpc_submit_transaction Pushes a signed raw transaction to the network. Write EventManagerService_CreateTrigger Create a new trigger Adds a trigger to a manager to listen for specific blockchain activ Write EventManagerService_UpdateTrigger Update a trigger Allows modification of a trigger Read rpc_block_range_info Fetches basic info for a contiguous block range (start and end height). Read brc20_transfer_inscriptions_by_address Returns all unspent BRC20 transfer inscriptions residing at the address. This endpoint is Read activity_by_inscription Lists all transactions that have involved the given inscription, starting from its origin

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about rune_utxos_by_address

What does the rune_utxos_by_address tool do? +

Return all UTxOs controlled by the specified address or script pubkey which contain runes, with the option to filter by a specific rune kind. It is categorised as a Read tool in the Maestro MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on rune_utxos_by_address? +

Register the Maestro MCP Server MCP server in PolicyLayer and add a rule for rune_utxos_by_address: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Maestro MCP Server. Nothing to install.

What risk level is rune_utxos_by_address? +

rune_utxos_by_address is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit rune_utxos_by_address? +

Yes. Add a rate_limit block to the rune_utxos_by_address rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block rune_utxos_by_address completely? +

Set action: deny in the PolicyLayer policy for rune_utxos_by_address. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides rune_utxos_by_address? +

rune_utxos_by_address is provided by the Maestro MCP Server MCP server (maestro-org/maestro-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Maestro MCP Server tool call.

Start from Maestro MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →