This record as markdown: /tools/io-fusionauth-mcp-api/deletelambdawithid.md
What deleteLambdaWithId does on Fusionauth
AI agents call deleteLambdaWithId to permanently remove resources in Fusionauth, typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Why deleteLambdaWithId is rated Critical
This tool permanently removes a lambda function by ID. Deletion is an irreversible operation with no undo capability. While the blast radius is scoped to a specific lambda (mitigating factors), the destruction of application logic could disrupt critical authentication or authorization workflows in FusionAuth.
From the tool's definition Tool name contains "delete" and description states "Deletes the lambda for the given Id" — indicating irreversible removal of a lambda function.
Attacks that exploit this kind of access
The rule that runs deleteLambdaWithId safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Fusionauth, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For deleteLambdaWithId, this is the rule to start with:
deleteLambdaWithId is removed from the agent's tool list entirely, so the agent never calls it. The rest of the server keeps working.
The button opens the PolicyLayer dashboard: create your workspace, connect Fusionauth, apply this rule, and every deleteLambdaWithId call is checked against it from then on.
Questions about deleteLambdaWithId
Deletes the lambda for the given Id. It is categorised as a Destructive tool in the Fusionauth MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Fusionauth MCP server in PolicyLayer and add a rule for deleteLambdaWithId: 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 Fusionauth. Nothing to install.
deleteLambdaWithId 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 deleteLambdaWithId 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 deleteLambdaWithId. 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.
deleteLambdaWithId is provided by the Fusionauth MCP server (@fusionauth/mcp-api). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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