List all Yamcs instances.
AI agents call list_instances to retrieve information from Yamcs MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only operation that queries and returns a list of existing Yamcs instances. It has no capability to create, modify, delete, execute commands, or trigger external actions. The blast radius of misuse is minimal—an AI agent listing instances cannot directly harm the system or commit irreversible changes.
From the tool's definition Tool name is 'list_instances' and description states 'List all Yamcs instances' — a query operation that retrieves information without modification or side effects.
Attacks that exploit this kind of access
List all Yamcs instances. It is categorised as a Read tool in the Yamcs MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Yamcs MCP Server MCP server in PolicyLayer and add a rule for list_instances: 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 Yamcs MCP Server. Nothing to install.
list_instances 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_instances 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_instances. 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_instances is provided by the Yamcs MCP Server MCP server (paulmramirez/yamcs-mcp-server). 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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