AI agents use pass__update_item to create or update resources in Proton-MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Proton-MCP environment.
This tool modifies existing credentials in Proton Pass, which is a password manager. While reversible (Write category), the severity is high because: (1) credentials are highly sensitive security assets, (2) unauthorized modification could compromise user accounts across multiple services, (3) an AI agent with access could alter stored passwords or authentication details with significant impact.
From the tool's definition Tool name 'pass__update_item' and description 'Update an existing credential in Proton Pass' explicitly indicate modification of stored sensitive data (credentials). The term 'update' confirms reversible modification rather than deletion or destruction.
Documented attack patterns abuse exactly the kind of access pass__update_item gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Proton-MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for pass__update_item:
{
"version": "1",
"default": "deny",
"tools": {
"pass__update_item": {
"limits": [
{
"counter": "pass__update_item_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}pass__update_item 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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Update an existing credential in Proton Pass. It is categorised as a Write tool in the Proton-MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Proton- MCP server in PolicyLayer and add a rule for pass__update_item: 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 Proton-MCP. Nothing to install.
pass__update_item 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 pass__update_item 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 pass__update_item. 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.
pass__update_item is provided by the Proton- MCP server (jorgenclaw/proton-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Proton-MCP, 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.
36 Proton-MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.