AI agents use contactsNotesSet to create or update resources in Telegram MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Telegram MCP Server environment.
This tool creates or modifies contact notes, which are data attributes that can be changed or cleared. While this is a Write operation (reversible), the severity is medium rather than low because contact information could be corrupted or overwritten by an AI agent if given incorrect instructions, potentially impacting user data integrity and trust in their contact database.
From the tool's definition Tool name 'contactsNotesSet' and description 'Sets notes for a contact' indicate a write operation that modifies contact metadata. The 'Set' verb and the context of setting notes (a mutable attribute) classify this as a reversible data modification.
Documented attack patterns abuse exactly the kind of access contactsNotesSet gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Telegram MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for contactsNotesSet:
{
"version": "1",
"default": "deny",
"tools": {
"contactsNotesSet": {
"limits": [
{
"counter": "contactsnotesset_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}contactsNotesSet 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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Sets notes for a contact. It is categorised as a Write tool in the Telegram MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Telegram MCP Server MCP server in PolicyLayer and add a rule for contactsNotesSet: 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 Telegram MCP Server. Nothing to install.
contactsNotesSet 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 contactsNotesSet 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 contactsNotesSet. 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.
contactsNotesSet is provided by the Telegram MCP Server MCP server (kfastov/tgcli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Telegram 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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38 Telegram MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.