get_user_instances
AI agents call get_user_instances to retrieve information from Nebulablock without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool appears to retrieve user instances—likely a query operation returning instance information without modification capability. The 'get_' prefix and empty description suggest a simple read operation. Confidence is 0.85 rather than higher because the description is missing, leaving room for ambiguity about exact scope, though context from sibling tools strongly suggests read-only behavior.
From the tool's definition Tool name 'get_user_instances' combined with 'list_' pattern of sibling tools (list_api_keys) and other 'get_' prefixed tools (get_computing_products, get_user_credit_balance, get_user_instance_detail) indicates data retrieval with no side effects.
Attacks that exploit this kind of access
get_user_instances. It is categorised as a Read tool in the Nebulablock MCP Server, which means it retrieves data without modifying state.
Register the Nebulablock MCP server in PolicyLayer and add a rule for get_user_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 Nebulablock. Nothing to install.
get_user_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 get_user_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 get_user_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.
get_user_instances is provided by the Nebulablock MCP server (nebula-block-data/nebulablock-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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