Create or update a Kestra flow from a raw YAML definition. Returns the created or updated flow's JSON metadata.
AI agents use create_flow_from_yaml to create or update resources in Kestra Python MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Kestra Python MCP Server environment.
This tool modifies workflow definitions in a potentially persistent manner. While 'update' is reversible (a Write operation rather than Destructive), the blast radius is high because: (1) malicious YAML could define workflows that execute harmful operations when triggered, (2) overwriting existing flows could disrupt critical automation, and (3) the tool accepts raw, unvalidated YAML input.
From the tool's definition Tool description states 'Create or update a Kestra flow from a raw YAML definition'. The verbs 'create' and 'update' are explicitly Write operations.
Documented attack patterns abuse exactly the kind of access create_flow_from_yaml gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Kestra Python MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for create_flow_from_yaml:
{
"version": "1",
"default": "deny",
"tools": {
"create_flow_from_yaml": {
"limits": [
{
"counter": "create_flow_from_yaml_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_flow_from_yaml stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Create or update a Kestra flow from a raw YAML definition. Returns the created or updated flow's JSON metadata. It is categorised as a Write tool in the Kestra Python MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Kestra Python MCP Server MCP server in PolicyLayer and add a rule for create_flow_from_yaml: 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 Kestra Python MCP Server. Nothing to install.
create_flow_from_yaml 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 create_flow_from_yaml 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 create_flow_from_yaml. 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.
create_flow_from_yaml is provided by the Kestra Python MCP Server MCP server (kestra-io/mcp-server-python). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Kestra Python MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
39 Kestra Python MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.