Invoke any tool on the SettleGrid marketplace by its slug. Pass arguments as a JSON object. Free showcase tools work without an API key. Paid tools route through the Smart Proxy and require an API key (passed via the x-api-key header on the MCP connection). Use search_tools or list_marketplace_to...
Part of the Settlegrid Discovery server.
Free to start. No card required.
AI agents invoke call_tool to trigger processes or run actions in Settlegrid Discovery. 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_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. PolicyLayer 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.
{
"version": "1",
"default": "deny",
"tools": {
"call_tool": {
"limits": [
{
"counter": "call_tool_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}See the full Settlegrid Discovery policy for all 6 tools.
These attack patterns abuse exactly the kind of access call_tool gives an agent. Each links to the full case and the policy that stops it:
Other execute tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Invoke any tool on the SettleGrid marketplace by its slug. Pass arguments as a JSON object. Free showcase tools work without an API key. Paid tools route through the Smart Proxy and require an API key (passed via the x-api-key header on the MCP connection). Use search_tools or list_marketplace_tools first to find the right tool and its slug.. It is categorised as a Execute tool in the Settlegrid Discovery MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Settlegrid Discovery MCP server in PolicyLayer and add a rule for call_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 Settlegrid Discovery. Nothing to install.
call_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_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 call_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_tool is provided by the Settlegrid Discovery MCP server (settlegrid/settlegrid-discovery). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 6 Settlegrid Discovery tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.