send_message_to_session

THE RISK

Medium Risk

Why send_message_to_session needs a policy

This tool sends messages to a Devin AI session and Slack thread. It creates/posts new messages (reversible write operation). While it could trigger actions in Devin, the primary function described is messaging/communication, not executing code directly. Misuse could send unauthorized instructions to Devin sessions or spam Slack threads.

From the tool's definition Send a message to an existing Devin session and optionally to the associated Slack thread

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

POLICY

How to control send_message_to_session

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "send_message_to_session": {
      "limits": [
        {
          "counter": "send_message_to_session_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

send_message_to_session stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

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

LIMIT THIS TOOL →

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EXPLORE

Related tools and policies

More MCP-Devin tools

Execute create_devin_session Create a new Devin session for code development and post the task to Slack. Note: This is Read get_devin_session Get information about an existing Devin session and optionally fetch associated Slack mess Read get_organization_info Get information about the current Devin organization Read list_devin_sessions List all Devin sessions

All 5 MCP-Devin tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about send_message_to_session

What does the send_message_to_session tool do? +

Send a message to an existing Devin session and optionally to the associated Slack thread. It is categorised as a Write tool in the MCP-Devin MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on send_message_to_session? +

Register the MCP-Devin MCP server in PolicyLayer and add a rule for send_message_to_session: 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 MCP-Devin. Nothing to install.

What risk level is send_message_to_session? +

send_message_to_session is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit send_message_to_session? +

Yes. Add a rate_limit block to the send_message_to_session 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_message_to_session completely? +

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

send_message_to_session is provided by the MCP-Devin MCP server (kazuph/mcp-devin). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP-Devin tool call.

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

CHECK YOUR STACK →