esplora_block_txid_by_index

THE RISK

Low Risk

Why esplora_block_txid_by_index needs a policy

This tool retrieves existing transaction information from the Bitcoin blockchain without creating, modifying, deleting, or executing any operations. It is a simple data lookup operation on immutable blockchain history. The blast radius of misuse is minimal—an agent could only spam queries or exhaust rate limits, not corrupt data or cause financial harm.

From the tool's definition Tool returns transaction data at a specified index within a block. The verb 'Returns' and the read-only nature of querying blockchain transaction data indicate no side effects or state modifications.

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

POLICY

How to control esplora_block_txid_by_index

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 esplora_block_txid_by_index:

policy.json

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

esplora_block_txid_by_index 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.

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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 esplora_block_txid_by_index

What does the esplora_block_txid_by_index tool do? +

Returns the transaction at index :index within the specified block. 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 esplora_block_txid_by_index? +

Register the Maestro MCP Server MCP server in PolicyLayer and add a rule for esplora_block_txid_by_index: 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 esplora_block_txid_by_index? +

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

Can I rate-limit esplora_block_txid_by_index? +

Yes. Add a rate_limit block to the esplora_block_txid_by_index 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 esplora_block_txid_by_index completely? +

Set action: deny in the PolicyLayer policy for esplora_block_txid_by_index. 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 esplora_block_txid_by_index? +

esplora_block_txid_by_index 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.

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