AI agents use update_contact to create or update resources in Twenty MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Twenty MCP Server environment.
This tool modifies contact records in a CRM system but does not delete or irreversibly destroy data. The change can be undone by updating the contact again with previous values. It is categorized as Write rather than Execute because it targets a specific data entity (contact) rather than executing arbitrary code or commands.
From the tool's definition The tool name is 'update_contact' and the description explicitly states 'Update an existing contact in Twenty CRM'. This performs a reversible modification to existing data.
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 Twenty MCP Server, 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 in Twenty CRM. It is categorised as a Write tool in the Twenty MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Twenty MCP Server 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 Twenty MCP Server. 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 Twenty MCP Server MCP server (jezweb/twenty-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Twenty MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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29 Twenty MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.