Explicitly close a sncro session — "Finished With Engines". Call this when you are done debugging and will not need the sncro tools again in this conversation. After this returns, all sncro tool calls on this key will refuse with a SESSION_CLOSED message — that is your signal to stop trying to us...
Risk signalsHandles credentials or secrets (secret)
Part of the Sncro server.
Free to start. No card required.
AI agents invoke end_session to trigger processes or run actions in Sncro. 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.
end_session 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": {
"end_session": {
"limits": [
{
"counter": "end_session_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}See the full Sncro policy for all 12 tools.
These attack patterns abuse exactly the kind of access end_session 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.
Explicitly close a sncro session — "Finished With Engines". Call this when you are done debugging and will not need the sncro tools again in this conversation. After this returns, all sncro tool calls on this key will refuse with a SESSION_CLOSED message — that is your signal to stop trying to use them and not apologise about it. Use it when: - The original problem is solved and the conversation has moved on - The user explicitly says "we're done with sncro for now" - You're entering a long stretch of work that won't need browser visibility The session can't be reopened. If you need browser visibility later, ask the user whether to start a new one with create_session.. It is categorised as a Execute tool in the Sncro MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Sncro MCP server in PolicyLayer and add a rule for end_session: 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 Sncro. Nothing to install.
end_session 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 end_session 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 end_session. 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.
end_session is provided by the Sncro MCP server (https://relay.sncro.net/tools/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 12 Sncro 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.