Given a source node and a list of target nodes, a directed spanning tree in which there exists a path from the source node to each of the target nodes is called a Directed Steiner Tree.
AI agents call minimum_directed_steiner_tree to retrieve information from Neo4j Gds without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves graph structure information by computing a specific subgraph (Directed Steiner Tree) that satisfies certain path properties. It is analogous to other graph algorithms on this server (breadth_first_search, shortest_path variants) which are read-only queries. The operation has no side effects on the database—it analyzes existing graph structure without creating, modifying, or deleting data.
From the tool's definition Tool computes and returns a 'directed spanning tree' given source and target nodes. The description indicates a graph query/analysis operation with no mention of modifying, deleting, or executing external operations.
Attacks that exploit this kind of access
Given a source node and a list of target nodes, a directed spanning tree in which there exists a path from the source node to each of the target nodes is called a Directed Steiner Tree. It is categorised as a Read tool in the Neo4j Gds MCP Server, which means it retrieves data without modifying state.
Register the Neo4j Gds MCP server in PolicyLayer and add a rule for minimum_directed_steiner_tree: 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 Neo4j Gds. Nothing to install.
minimum_directed_steiner_tree 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 minimum_directed_steiner_tree 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 minimum_directed_steiner_tree. 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.
minimum_directed_steiner_tree is provided by the Neo4j Gds MCP server (neo4j-contrib/gds-agent). 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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