Validate an email address: RFC-5322 syntax check, domain DNS resolution (does the domain exist?), and disposable-provider detection (Mailinator, 10minutemail, GuerrillaMail, etc.). Returns a single confidence verdict plus the underlying signals so agents can decide whether to send. Use before mai...
Part of the Onyx Mcp server.
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AI agents call onyx_email_validate to retrieve information from Onyx Mcp without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though onyx_email_validate only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"onyx_email_validate": {}
}
}See the full Onyx Mcp policy for all 67 tools.
These attack patterns abuse exactly the kind of access onyx_email_validate gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Validate an email address: RFC-5322 syntax check, domain DNS resolution (does the domain exist?), and disposable-provider detection (Mailinator, 10minutemail, GuerrillaMail, etc.). Returns a single confidence verdict plus the underlying signals so agents can decide whether to send. Use before mailing list signups, password-reset flows, or sales-lead capture to filter out trash addresses cheaply. ~30-80ms typical. (price: $0.002 USDC, tier: metered). It is categorised as a Read tool in the Onyx Mcp MCP Server, which means it retrieves data without modifying state.
Register the Onyx MCP server in PolicyLayer and add a rule for onyx_email_validate: 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 Onyx Mcp. Nothing to install.
onyx_email_validate is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the onyx_email_validate 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 onyx_email_validate. 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.
onyx_email_validate is provided by the Onyx MCP server (https://onyx-actions.onrender.com/mcp/). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 67 Onyx Mcp tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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