AI agents use notes.save_attachment to create or update resources in Nucleus Apple — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Nucleus Apple environment.
This tool saves/exports an attachment to a specified file path, which is a write operation to the filesystem. It creates or overwrites a file at the given path. While this is reversible (the file can be deleted), it could overwrite existing files, giving it medium severity. The description is brief, so confidence is slightly reduced.
From the tool's definition 'Export an attachment to a file path' — writes a file to the filesystem
Documented attack patterns abuse exactly the kind of access notes.save_attachment gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Nucleus Apple, and nothing reaches the server without passing your rules. This is the rule we recommend for notes.save_attachment:
{
"version": "1",
"default": "deny",
"tools": {
"notes.save_attachment": {
"limits": [
{
"counter": "notes.save_attachment_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}notes.save_attachment 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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Export an attachment to a file path. It is categorised as a Write tool in the Nucleus Apple MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Nucleus Apple MCP server in PolicyLayer and add a rule for notes.save_attachment: 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 Nucleus Apple. Nothing to install.
notes.save_attachment 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 notes.save_attachment 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 notes.save_attachment. 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.
notes.save_attachment is provided by the Nucleus Apple MCP server (zish-rob-crur/nucleus-apple-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Nucleus Apple, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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30 Nucleus Apple tools catalogued and risk-classified — across an index of 43,000+ MCP servers.