AI agents use update_contact to create or update resources in PhonePi MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PhonePi MCP environment.
This tool modifies existing contact information, which is a Write operation—data is changed but the change is reversible (contacts can be updated again or restored). It has medium severity because contact data is personal information, and unauthorized updates could lead to misdirected communications or confusion, but the impact is limited to a single contact record and is not destructive or financial in nature.
From the tool's definition Tool name 'update_contact' and description 'Update an existing contact' indicate reversible modification of contact data stored on the smartphone.
Documented attack patterns abuse exactly the kind of access update_contact gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and PhonePi MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for update_contact:
{
"version": "1",
"default": "deny",
"tools": {
"update_contact": {
"limits": [
{
"counter": "update_contact_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_contact 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 contact. It is categorised as a Write tool in the PhonePi MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the PhonePi MCP server in PolicyLayer and add a rule for update_contact: 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 PhonePi MCP. Nothing to install.
update_contact 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 update_contact 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 update_contact. 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.
update_contact is provided by the PhonePi MCP server (priyankark/phonepi-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 22 PhonePi MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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22 PhonePi MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.