List named graphs and ontologies available in the endpoint. Args: None Returns: - graphs: List of named graphs in the endpoint - ontologies: List of owl:Ontology and skos:ConceptScheme resources When to use this vs X: - use this for a quick structural overview of the endpoint - use \
AI agents call explore_catalog to retrieve information from Schema Gov It MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a discovery/query operation that retrieves structural metadata about the data catalog without modifying state or triggering side effects. It is purely informational, suitable for exploration of available resources. Classified as Read with low severity due to minimal blast radius if misused by an agent—the worst outcome would be inefficient queries or information disclosure of public catalog structure.
From the tool's definition Tool lists named graphs and ontologies from the endpoint. No mutations occur: 'List named graphs and ontologies available' and returns descriptive metadata (graphs, ontologies). No data creation, deletion, or external operations.
Documented attack patterns abuse exactly the kind of access explore_catalog gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Schema Gov It MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for explore_catalog:
{
"version": "1",
"default": "deny",
"tools": {
"explore_catalog": {}
}
}explore_catalog is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List named graphs and ontologies available in the endpoint. Args: None Returns: - graphs: List of named graphs in the endpoint - ontologies: List of owl:Ontology and skos:ConceptScheme resources When to use this vs X: - use this for a quick structural overview of the endpoint - use \. It is categorised as a Read tool in the Schema Gov It MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Schema Gov It MCP Server MCP server in PolicyLayer and add a rule for explore_catalog: 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 Schema Gov It MCP Server. Nothing to install.
explore_catalog 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 explore_catalog 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 explore_catalog. 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.
explore_catalog is provided by the Schema Gov It MCP Server MCP server (italia/dati-semantic-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Schema Gov It MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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47 Schema Gov It MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.