Search messages by subject keywords with optional date range. Auto-connects if not already connected.
AI agents call search_by_subject to retrieve information from Mcp Mail Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries existing email messages based on subject criteria, returning results without altering data. Although it operates on email (sensitive data), the operation itself is read-only with minimal blast radius — an AI agent misusing this tool could only exfiltrate information accessible to the authenticated account, not modify or delete messages, execute commands, or trigger financial transactions.
From the tool's definition Tool name is 'search_by_subject' and description states it 'Search messages by subject keywords' — a retrieval operation with 'optional date range' parameter. No modifications, deletions, or external operations are described.
Attacks that exploit this kind of access
Search messages by subject keywords with optional date range. Auto-connects if not already connected. It is categorised as a Read tool in the Mcp Mail Server MCP Server, which means it retrieves data without modifying state.
Register the Mcp Mail Server MCP server in PolicyLayer and add a rule for search_by_subject: 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 Mcp Mail Server. Nothing to install.
search_by_subject 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 search_by_subject 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 search_by_subject. 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.
search_by_subject is provided by the Mcp Mail Server MCP server (mcp-mail-server). 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.
Teams ship this data inside their own products. See what a licence covers →