Add a new email account. For Gmail: opens a browser for OAuth. For IMAP/JMAP: stores encrypted credentials. Sensitive fields (username, password) can also be set via environment variables.
Accepts URL/endpoint input (host); Handles credentials or secrets (password); High parameter count (11 properties)
Part of the Mailbox MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents use authenticate to create or modify resources in Mailbox. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call authenticate repeatedly, creating or modifying resources faster than any human could review. Intercept's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Mailbox.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
tools:
authenticate:
rules:
- action: allow
rate_limit:
max: 30
window: 60See the full Mailbox policy for all 49 tools.
Agents calling write-class tools like authenticate have been implicated in these attack patterns. Read the full case and prevention policy for each:
Other tools in the Write risk category across the catalogue. The same policy patterns (rate-limit, validate) apply to each.
Add a new email account. For Gmail: opens a browser for OAuth. For IMAP/JMAP: stores encrypted credentials. Sensitive fields (username, password) can also be set via environment variables.. It is categorised as a Write tool in the Mailbox MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Add a rule in your Intercept YAML policy under the tools section for authenticate. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Mailbox MCP server.
authenticate 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 authenticate rule in your Intercept 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 Intercept policy for authenticate. 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.
authenticate is provided by the Mailbox MCP server (mailbox-mcp). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic policy on every MCP tool call. Per-identity grants. Full audit log.