指定したmessageIdとattachmentIdで添付ファイルを取得します。 ファイルはDownloadsフォルダに保存されます。 attachmentIdはattachmentsの各attachmentのnameでありファイル名となることが多いです(invoice.pdfなど)。 引数: - messageId: メッセージID（必須） - attachmentId: 添付ファイルID（必須） - outputFilename: 保存時のファイル名（オプション）
AI agents call gmail_download_attachment to retrieve information from Mcp Gmail Gas without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves/downloads an existing attachment without modifying, deleting, or executing anything. It is purely a data retrieval operation. While it does write the file to disk, the primary action is fetching existing data from Gmail, and the local file write is incidental to the read operation. No reversible modifications are made to Gmail data itself, and no irreversible deletions or code execution occur.
From the tool's definition Tool downloads and retrieves an attachment from a Gmail message specified by messageId and attachmentId, then saves it to the Downloads folder.
Documented attack patterns abuse exactly the kind of access gmail_download_attachment gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Gmail Gas, and nothing reaches the server without passing your rules. This is the rule we recommend for gmail_download_attachment:
{
"version": "1",
"default": "deny",
"tools": {
"gmail_download_attachment": {}
}
}gmail_download_attachment is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
指定したmessageIdとattachmentIdで添付ファイルを取得します。 ファイルはDownloadsフォルダに保存されます。 attachmentIdはattachmentsの各attachmentのnameでありファイル名となることが多いです(invoice.pdfなど)。 引数: - messageId: メッセージID（必須） - attachmentId: 添付ファイルID（必須） - outputFilename: 保存時のファイル名（オプション）. It is categorised as a Read tool in the Mcp Gmail Gas MCP Server, which means it retrieves data without modifying state.
Register the Mcp Gmail Gas MCP server in PolicyLayer and add a rule for gmail_download_attachment: 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 Gmail Gas. Nothing to install.
gmail_download_attachment 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 gmail_download_attachment 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 gmail_download_attachment. 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.
gmail_download_attachment is provided by the Mcp Gmail Gas MCP server (kazuph/mcp-gmail-gas). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mcp Gmail Gas, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
3 Mcp Gmail Gas tools catalogued and risk-classified — across an index of 43,000+ MCP servers.