AI agents call a2a_discover to retrieve information from Wmux without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves information about available workspaces and agents without modifying, executing, or deleting anything. It is a pure data retrieval operation, fitting the 'Read' category. The low severity reflects minimal blast radius—even if an agent misuses this discovery function, it only gains visibility into workspace names and availability, not access to sensitive data or system operations.
From the tool's definition Tool name 'a2a_discover' and description 'List all available workspaces/agents and their names' indicate a query/enumeration operation with no side effects.
Attacks that exploit this kind of access
List all available workspaces/agents and their names. ALWAYS call this first when the user references a workspace by number or name (e.g. It is categorised as a Read tool in the Wmux MCP Server, which means it retrieves data without modifying state.
Register the Wmux MCP server in PolicyLayer and add a rule for a2a_discover: 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 Wmux. Nothing to install.
a2a_discover 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 a2a_discover 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 a2a_discover. 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.
a2a_discover is provided by the Wmux MCP server (openwong2kim/wmux). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
a2a_discover is one line of Wmux's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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