send_agent_message · Tenzro Ledger MCP: Risk & Policy

WHAT IT DOES

What send_agent_message does on Tenzro Ledger MCP

AI agents invoke send_agent_message to trigger actions in Tenzro Ledger MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why send_agent_message needs a policy

This tool triggers an external operation — dispatching a message between agents via a protocol. It is not a simple data read or write; it causes an action in an external system (agent-to-agent communication), which could trigger downstream agent behaviors. The blast radius is medium since a misused message could cause unintended agent actions, but it doesn't directly move money or destroy data.

From the tool's definition Send a message from one agent to another via the A2A protocol

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_agent_message Rate-limited

send_agent_message stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "send_agent_message": {
      "limits": [
        {
          "counter": "send_agent_message_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Tenzro Ledger MCP, so you can run agents against it safely.

FAQ

Questions about send_agent_message

What does the send_agent_message tool do? +

Send a message from one agent to another via the A2A protocol. It is categorised as a Execute tool in the Tenzro Ledger MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on send_agent_message? +

Register the Tenzro Ledger MCP server in PolicyLayer and add a rule for send_agent_message: 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 Tenzro Ledger MCP. Nothing to install.

What risk level is send_agent_message? +

send_agent_message is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit send_agent_message? +

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

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

send_agent_message is provided by the Tenzro Ledger MCP server (https://canton-mcp.tenzro.network/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.