encrypt_metadata_fields · Todos MCP: Risk & Policy

WHAT IT DOES

What encrypt_metadata_fields does on Todos

AI agents use encrypt_metadata_fields to create or update resources in Todos — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Todos environment.

WHY IT NEEDS A POLICY

Why encrypt_metadata_fields needs a policy

This tool modifies metadata by encrypting sensitive fields, which is a reversible data transformation (data can be decrypted). It does not delete data, execute arbitrary code, or move money. The primary effect is writing/updating the metadata object with encrypted values. Severity is medium because misconfiguration (wrong key, unintended fields) could corrupt or make data inaccessible.

From the tool's definition 'Encrypt sensitive fields in a metadata object using local key' — transforms/modifies data in place using encryption

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

encrypt_metadata_fields Rate-limited

encrypt_metadata_fields 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "encrypt_metadata_fields": {
      "limits": [
        {
          "counter": "encrypt_metadata_fields_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Todos, so you can run agents against it safely.

FAQ

Questions about encrypt_metadata_fields

What does the encrypt_metadata_fields tool do? +

Encrypt sensitive fields in a metadata object using local key (TODOS_ENCRYPTION_KEY or key file). It is categorised as a Write tool in the Todos MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on encrypt_metadata_fields? +

Register the Todos MCP server in PolicyLayer and add a rule for encrypt_metadata_fields: 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 Todos. Nothing to install.

What risk level is encrypt_metadata_fields? +

encrypt_metadata_fields is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit encrypt_metadata_fields? +

Yes. Add a rate_limit block to the encrypt_metadata_fields 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.

How do I block encrypt_metadata_fields completely? +

Set action: deny in the PolicyLayer policy for encrypt_metadata_fields. 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.

What MCP server provides encrypt_metadata_fields? +

encrypt_metadata_fields is provided by the Todos MCP server (@hasna/todos). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.