Invoke a WebMCP tool declared by the current page
AI agents invoke invoke_webmcp_tool to trigger actions in Webclaw. 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.
This tool executes code or operations whose effects entirely depend on runtime arguments (which WebMCP tools are declared and what they do). It bridges an MCP agent to arbitrary web-based operations, giving the agent capability to trigger any functionality a webpage exposes. This is Execute rather than just Write because WebMCP tools can perform any action (read, write, delete, external calls).
From the tool's definition Tool description states 'Invoke a WebMCP tool declared by the current page' — this runs arbitrary code/operations exposed by web pages.
Documented attack patterns abuse exactly the kind of access invoke_webmcp_tool gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Webclaw, and nothing reaches the server without passing your rules. This is the rule we recommend for invoke_webmcp_tool:
{
"version": "1",
"default": "deny",
"tools": {
"invoke_webmcp_tool": {
"limits": [
{
"counter": "invoke_webmcp_tool_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}invoke_webmcp_tool 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.
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Invoke a WebMCP tool declared by the current page. It is categorised as a Execute tool in the Webclaw MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Webclaw MCP server in PolicyLayer and add a rule for invoke_webmcp_tool: 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 Webclaw. Nothing to install.
invoke_webmcp_tool is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the invoke_webmcp_tool 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 invoke_webmcp_tool. 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.
invoke_webmcp_tool is provided by the Webclaw MCP server (kuroko1t/webclaw). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Webclaw, 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.
21 Webclaw tools catalogued and risk-classified — across an index of 43,000+ MCP servers.