Post a message into a Conversation. Fanned out to all participants via their channel (SMS / WhatsApp / chat).
AI agents use send_conversation_message to create or update resources in Mcp Ap2 — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp Ap2 environment.
This is a Write operation because it creates new communication data that is stored and delivered. Severity is medium because while messages can be sent to multiple people at scale, they are reversible (can be acknowledged/clarified), do not directly manipulate financial data or critical system state, and the blast radius is limited to conversation context rather than system-wide impact.
From the tool's definition Tool performs 'Post a message into a Conversation' which creates new data (a message) that is distributed to multiple participants. Description confirms it writes/sends data ('Fanned out to all participants via their channel').
Documented attack patterns abuse exactly the kind of access send_conversation_message gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Ap2, and nothing reaches the server without passing your rules. This is the rule we recommend for send_conversation_message:
{
"version": "1",
"default": "deny",
"tools": {
"send_conversation_message": {
"limits": [
{
"counter": "send_conversation_message_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
} send_conversation_message 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.
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Post a message into a Conversation. Fanned out to all participants via their channel (SMS / WhatsApp / chat). It is categorised as a Write tool in the Mcp Ap2 MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Mcp Ap2 MCP server in PolicyLayer and add a rule for send_conversation_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 Mcp Ap2. Nothing to install.
send_conversation_message is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the send_conversation_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.
Set action: deny in the PolicyLayer policy for send_conversation_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.
send_conversation_message is provided by the Mcp Ap2 MCP server (@codespar/mcp-ap2). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mcp Ap2, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
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