Replace (update) a journey draft. Full document replacement — include all nodes and properties in the body. Call publish_journey afterwards to make changes live, or pass state: "PUBLISHED" to publish immediately. Send node template IDs must already be scoped to this journey.
Part of the Courier server.
Free to start. No card required.
AI agents use replace_journey to create or modify resources in Courier. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call replace_journey repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Courier.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"replace_journey": {
"limits": [
{
"counter": "replace_journey_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Courier policy for all 123 tools.
These attack patterns abuse exactly the kind of access replace_journey gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Replace (update) a journey draft. Full document replacement — include all nodes and properties in the body. Call publish_journey afterwards to make changes live, or pass state: "PUBLISHED" to publish immediately. Send node template IDs must already be scoped to this journey.. It is categorised as a Write tool in the Courier MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Courier MCP server in PolicyLayer and add a rule for replace_journey: 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 Courier. Nothing to install.
replace_journey is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the replace_journey 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 replace_journey. 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.
replace_journey is provided by the Courier MCP server (https://mcp.courier.com). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 123 Courier 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.