AI agents call fetch_more_history to retrieve information from Whatsapp without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Although the tool persists data to local storage, the primary function is retrieving/querying existing messages from WhatsApp. No data is created, modified, deleted, or executed. The persistence to local store is a side effect of the read operation, not a write operation that creates new data. This falls squarely within the Read category as it fetches historical chat data.
From the tool's definition Tool description states 'Pull older messages for a chat from WhatsApp and persist to the local store' and server is described as 'read-only interface to WhatsApp'. The action retrieves historical message data without modification or deletion.
Attacks that exploit this kind of access
Pull older messages for a chat from WhatsApp and persist to the local store. Use when get_chat_messages does not reach far enough back. Returns {fetched_count, oldest_in_store_timestamp}. It is categorised as a Read tool in the Whatsapp MCP Server, which means it retrieves data without modifying state.
Register the Whatsapp MCP server in PolicyLayer and add a rule for fetch_more_history: 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 Whatsapp. Nothing to install.
fetch_more_history is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the fetch_more_history 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 fetch_more_history. 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.
fetch_more_history is provided by the Whatsapp MCP server (joaohts/whatsapp-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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