txs_by_block

THE RISK

Low Risk

Why txs_by_block needs a policy

This tool queries blockchain data (transaction hashes in a block) and presents it without any capability to modify, execute code, delete, or move funds. It is a straightforward read-only lookup operation, making it low severity even in a financial context since it only exposes historical transaction information already public on the blockchain.

From the tool's definition Tool returns a list of transaction hashes from a specified block with pagination support—purely a data retrieval operation with no modifications, deletions, or side effects.

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

POLICY

How to control txs_by_block

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 txs_by_block:

policy.json

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

txs_by_block 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 →

Free to start. No card required.

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 txs_by_block

What does the txs_by_block tool do? +

Returns a list of all transaction hashes included in the specified block. Supports pagination for blocks with a large number of transactions. 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 txs_by_block? +

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

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

Can I rate-limit txs_by_block? +

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

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

txs_by_block 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 →