Discover other Codex peer sessions on this machine, optionally scoped by machine, current directory, or git repo.
AI agents call list_peers to retrieve information from Codex Peers MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
list_peers retrieves and lists metadata about active peer sessions without modifying, executing, or deleting anything. It is a discovery/query operation that returns information about other sessions. The optional scoping parameters are filters, not destructive or state-changing actions.
From the tool's definition Tool description states it 'Discover[s] other Codex peer sessions' with optional filtering by machine, directory, or git repo. The verb 'discover' and the read-only nature of querying peer metadata indicates pure information retrieval with no side effects.
Attacks that exploit this kind of access
Discover other Codex peer sessions on this machine, optionally scoped by machine, current directory, or git repo. It is categorised as a Read tool in the Codex Peers MCP MCP Server, which means it retrieves data without modifying state.
Register the Codex Peers MCP server in PolicyLayer and add a rule for list_peers: 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 Codex Peers MCP. Nothing to install.
list_peers 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_peers 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_peers. 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_peers is provided by the Codex Peers MCP server (jscianna/codex-peers-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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