save_document · AI-Canvas MCP Server MCP: Risk & Policy

WHAT IT DOES

What save_document does on AI-Canvas MCP Server

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

WHY IT NEEDS A POLICY

Why save_document needs a policy

The tool writes/persists design document data to storage. While reversible (files can be overwritten or deleted separately), it modifies persistent state and could overwrite existing documents if misused by an agent. The 'high' severity reflects potential data loss through accidental overwriting or saving malicious modifications to design documents.

From the tool's definition Tool name 'save_document' and description 'Save the current document to a file' indicate creation or modification of files on disk. This is a write operation that persists state changes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

save_document Rate-limited

save_document 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": {
    "save_document": {
      "limits": [
        {
          "counter": "save_document_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 AI-Canvas MCP Server, so you can run agents against it safely.

FAQ

Questions about save_document

What does the save_document tool do? +

Save the current document to a file. It is categorised as a Write tool in the AI-Canvas MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on save_document? +

Register the AI-Canvas MCP Server MCP server in PolicyLayer and add a rule for save_document: 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 AI-Canvas MCP Server. Nothing to install.

What risk level is save_document? +

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

Can I rate-limit save_document? +

Yes. Add a rate_limit block to the save_document 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 save_document completely? +

Set action: deny in the PolicyLayer policy for save_document. 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 save_document? +

save_document is provided by the AI-Canvas MCP Server MCP server (laoluojuhai/ai-canvas). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.