Return nodes transitively reachable from the source node.
AI agents call reachable_from to retrieve information from Trailmark MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns graph traversal results (nodes reachable from a source), performing a read-only analysis operation with no side effects on data or systems.
From the tool's definition Return nodes transitively reachable from the source node
Attacks that exploit this kind of access
Return nodes transitively reachable from the source node. It is categorised as a Read tool in the Trailmark MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Trailmark MCP Server MCP server in PolicyLayer and add a rule for reachable_from: 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 Trailmark MCP Server. Nothing to install.
reachable_from 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 reachable_from 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 reachable_from. 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.
reachable_from is provided by the Trailmark MCP Server MCP server (parsiya/trailmark-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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