Remove one top-level YAML frontmatter key.
AI agents call remove_frontmatter_key to permanently remove resources in Ast Editor — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
This tool removes a key from YAML frontmatter, which is an irreversible deletion of data. While the blast radius is limited to a single frontmatter key in a file (and file system changes could theoretically be undone via version control), the operation itself is a deletion that cannot be undone by the tool itself, placing it in the Destructive category.
From the tool's definition Remove one top-level YAML frontmatter key
Documented attack patterns abuse exactly the kind of access remove_frontmatter_key gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Ast Editor, and nothing reaches the server without passing your rules. This is the rule we recommend for remove_frontmatter_key:
{
"version": "1",
"default": "deny",
"hide": [
"remove_frontmatter_key"
]
}remove_frontmatter_key disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
Free to start. No card required.
Remove one top-level YAML frontmatter key. It is categorised as a Destructive tool in the Ast Editor MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Ast Editor MCP server in PolicyLayer and add a rule for remove_frontmatter_key: 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 Ast Editor. Nothing to install.
remove_frontmatter_key is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the remove_frontmatter_key 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 remove_frontmatter_key. 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.
remove_frontmatter_key is provided by the Ast Editor MCP server (kambleakash0/agent-skills). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Ast Editor, 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.
59 Ast Editor tools catalogued and risk-classified — across an index of 43,000+ MCP servers.