AI agents call list_identities to retrieve information from Tbird without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves metadata about email identities (names, addresses, send capabilities) from local Thunderbird configuration. It is a read-only query with no side effects, no code execution, and no data modification. The blast radius of misuse is minimal—an attacker learns what email accounts exist locally, which is reconnaissance-level risk. Appropriate to the Read category.
From the tool's definition Tool name and description indicate it 'List[s] send-from identities and whether each can send right now' — a query operation that retrieves identity configuration without modifying, deleting, or executing actions.
Attacks that exploit this kind of access
List send-from identities and whether each can send right now. It is categorised as a Read tool in the Tbird MCP Server, which means it retrieves data without modifying state.
Register the Tbird MCP server in PolicyLayer and add a rule for list_identities: 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 Tbird. Nothing to install.
list_identities 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 list_identities 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 list_identities. 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.
list_identities is provided by the Tbird MCP server (neil-zielsdorf/tbird-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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