[cost: free (pure CPU, no network) | read-only, no persistence] Run RFC 3261 / RFC 3325 / RFC 8224 / RFC 8225 / CTIA BCID compliance checks on a single raw SIP request (typically an INVITE) and return a list of findings. Catches the failure modes that silently break carrier interop: - Two From: h...
Part of the Sipflow server.
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AI agents invoke lint_sip_request to trigger processes or run actions in Sipflow. 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.
lint_sip_request 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": {
"lint_sip_request": {
"limits": [
{
"counter": "lint_sip_request_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}See the full Sipflow policy for all 22 tools.
These attack patterns abuse exactly the kind of access lint_sip_request 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.
[cost: free (pure CPU, no network) | read-only, no persistence] Run RFC 3261 / RFC 3325 / RFC 8224 / RFC 8225 / CTIA BCID compliance checks on a single raw SIP request (typically an INVITE) and return a list of findings. Catches the failure modes that silently break carrier interop: - Two From: headers in one request (RFC 3261 §7.3 / §20.20). - Missing CRLF between consecutive header lines (RFC 3261 §7.3). - ;tag= (or any other) parameter on P-Asserted-Identity / P-Preferred-Identity (RFC 3325 §9.1). - PASSporT orig.tn not matching the From caller TN (RFC 8224 §5). - PASSporT dest.tn not matching the To callee TN (RFC 8224 §5). - Non-canonical TN inside a PASSporT claim (RFC 8225 §5.2.1). - Branded display name in From with no ppt=rcd Identity header (CTIA BCID §5). Use FIRST when chasing 422 / 400 Bad Request / 484 Invalid FROM on a single INVITE - these usually have a structural cause this tool catches mechanically. Pair with: parse_sip_message for purely structural checks on any SIP message (responses included); validate_stir_shaken_identity for the cryptographic verdict on Identity headers; search_sip_docs({ sourceType: 'stir-shaken', ... }) to ground the explanation in RFC text.. It is categorised as a Execute tool in the Sipflow MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Sipflow MCP server in PolicyLayer and add a rule for lint_sip_request: 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 Sipflow. Nothing to install.
lint_sip_request 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 lint_sip_request 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 lint_sip_request. 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.
lint_sip_request is provided by the Sipflow MCP server (https://mcp.sipflow.dev/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 22 Sipflow tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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