Directly invoke a tool on one of the user's registered MCP servers by connection_id. Use this for one-off tool calls without activating the full server in this session. For repeated use, prefer activate_mcp so tools appear directly in the tool list as <server>__<tool>.
Part of the Clevername MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents invoke call_mcp_tool to trigger processes or run actions in Clevername. Execute operations can have side effects beyond the immediate call -- triggering builds, sending notifications, or starting workflows. Rate limits and argument validation are essential to prevent runaway execution.
call_mcp_tool can trigger processes with real-world consequences. An uncontrolled agent might start dozens of builds, send mass notifications, or kick off expensive compute jobs. Intercept enforces rate limits and validates arguments to keep execution within safe bounds.
Execute tools trigger processes. Rate-limit and validate arguments to prevent unintended side effects.
tools:
call_mcp_tool:
rules:
- action: allow
rate_limit:
max: 10
window: 60
validate:
required_args: trueSee the full Clevername policy for all 67 tools.
Agents calling execute-class tools like call_mcp_tool have been implicated in these attack patterns. Read the full case and prevention policy for each:
Other tools in the Execute risk category across the catalogue. The same policy patterns (rate-limit, validate) apply to each.
call_mcp_tool is one of the high-risk operations in Clevername. For the full severity-focused view — only the high-risk tools with their recommended policies — see the breakdown for this server, or browse all high-risk tools across every MCP server.
Directly invoke a tool on one of the user's registered MCP servers by connection_id. Use this for one-off tool calls without activating the full server in this session. For repeated use, prefer activate_mcp so tools appear directly in the tool list as <server>__<tool>.. It is categorised as a Execute tool in the Clevername MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Add a rule in your Intercept YAML policy under the tools section for call_mcp_tool. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Clevername MCP server.
call_mcp_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 call_mcp_tool rule in your Intercept 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 Intercept policy for call_mcp_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.
call_mcp_tool is provided by the Clevername MCP server (@clevername/clevername-mcp). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Open source. One binary. Zero dependencies.
npx -y @policylayer/intercept