AI agents call get_header to retrieve information from Imap without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves email message header metadata (To, From, Subject, Date, etc.) for a specified message UID. It performs a simple query operation on existing mailbox data without creating, modifying, deleting, or executing anything. The explicit use of 'Read' in the description confirms this is a passive information retrieval operation with no blast radius.
From the tool's definition Tool name 'get_header' and description 'Read message header for the given uid in directory' explicitly indicate data retrieval with no modification or side effects.
Attacks that exploit this kind of access
Read message header for the given uid in directory. It is categorised as a Read tool in the Imap MCP Server, which means it retrieves data without modifying state.
Register the Imap MCP server in PolicyLayer and add a rule for get_header: 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 Imap. Nothing to install.
get_header 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 get_header 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 get_header. 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.
get_header is provided by the Imap MCP server (vivier/imap-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
get_header is one line of Imap's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
Teams ship this data inside their own products. See what a licence covers →