Walk the HistoryMap of a lowered feature and return the chain of lineage entries that produced a named face ref. Inputs: feature_id ("auto" for last) and ref (string selector "name.slot" or a structured FaceRef / EdgeRef). Returns { chain, usedFallback }. Ships create/modify ops in this slice; sp...
Risk signalsAccepts file system path (file) · Accepts freeform code/query input (code)
Part of the Kernelcad server.
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AI agents call get_face_lineage to retrieve information from Kernelcad without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though get_face_lineage only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"get_face_lineage": {}
}
}See the full Kernelcad policy for all 48 tools.
These attack patterns abuse exactly the kind of access get_face_lineage gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Walk the HistoryMap of a lowered feature and return the chain of lineage entries that produced a named face ref. Inputs: feature_id ("auto" for last) and ref (string selector "name.slot" or a structured FaceRef / EdgeRef). Returns { chain, usedFallback }. Ships create/modify ops in this slice; split/delete classification is deferred.. It is categorised as a Read tool in the Kernelcad MCP Server, which means it retrieves data without modifying state.
Register the Kernelcad MCP server in PolicyLayer and add a rule for get_face_lineage: 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 Kernelcad. Nothing to install.
get_face_lineage 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_face_lineage 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_face_lineage. 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_face_lineage is provided by the Kernelcad MCP server (kernelcad). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 48 Kernelcad tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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