AI agents call list_sources to retrieve information from ContextCore without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Without an explicit description, classification relies on context: the server is designed for retrieval and search across indexed content. The 'list_' prefix strongly indicates a query/enumeration operation with no side effects. Sibling tools are uniformly Read-category utilities.
From the tool's definition Tool name 'list_sources' suggests listing or retrieving data. The empty description is uninformative, but given the server's purpose (indexing and retrieving local files) and sibling tools that are all Read operations (list_files, get_file_content,…
Documented attack patterns abuse exactly the kind of access list_sources gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and ContextCore, and nothing reaches the server without passing your rules. This is the rule we recommend for list_sources:
{
"version": "1",
"default": "deny",
"tools": {
"list_sources": {}
}
}list_sources is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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list_sources. It is categorised as a Read tool in the ContextCore MCP Server, which means it retrieves data without modifying state.
Register the ContextCore MCP server in PolicyLayer and add a rule for list_sources: 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 ContextCore. Nothing to install.
list_sources 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_sources 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_sources. 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_sources is provided by the ContextCore MCP server (lucifer-ux/contextcore). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from ContextCore, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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16 ContextCore tools catalogued and risk-classified — across an index of 43,000+ MCP servers.