AI agents use send_media_message to create or update resources in WhatsApp Web MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your WhatsApp Web MCP environment.
Sending a message is a Write operation—it creates new data (messages) in WhatsApp conversations reversibly (messages can be deleted). It is not Execute because it does not run arbitrary code or commands; it performs a specific messaging action. Severity is medium because misuse could spam contacts or send unintended content, but the blast radius is limited to messaging rather than data deletion or financial impact.
From the tool's definition Tool name 'send_media_message' indicates it sends media through WhatsApp, which modifies the state of conversations by adding new messages.
Documented attack patterns abuse exactly the kind of access send_media_message gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and WhatsApp Web MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for send_media_message:
{
"version": "1",
"default": "deny",
"tools": {
"send_media_message": {
"limits": [
{
"counter": "send_media_message_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}send_media_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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send_media_message. It is categorised as a Write tool in the WhatsApp Web MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the WhatsApp Web MCP server in PolicyLayer and add a rule for send_media_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 WhatsApp Web MCP. Nothing to install.
send_media_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_media_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_media_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_media_message is provided by the WhatsApp Web MCP server (pnizer/wweb-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 13 WhatsApp Web MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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13 WhatsApp Web MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.