Fork a knowledge base scope — creates an independent copy of all facts in the source scope under a new target scope name. Use for hypothetical reasoning ('What if Alice moves to London?') without modifying the main knowledge base. Similar to git branch for knowledge. Side effects: mutates state (...
Part of the Nocturnusai server.
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AI agents call fork_scope to retrieve information from Nocturnusai 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 fork_scope 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": {
"fork_scope": {}
}
}See the full Nocturnusai policy for all 16 tools.
These attack patterns abuse exactly the kind of access fork_scope 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.
Fork a knowledge base scope — creates an independent copy of all facts in the source scope under a new target scope name. Use for hypothetical reasoning ('What if Alice moves to London?') without modifying the main knowledge base. Similar to git branch for knowledge. Side effects: mutates state (additive) — creates a new scope with copied facts; source scope is unchanged. Auth: requires X-Tenant-ID header; FACT_WRITE permission when auth is enabled. Rate-limited per principal. Errors: VALIDATION_ERROR if targetScope is blank or already exists.. It is categorised as a Read tool in the Nocturnusai MCP Server, which means it retrieves data without modifying state.
Register the Nocturnusai MCP server in PolicyLayer and add a rule for fork_scope: 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 Nocturnusai. Nothing to install.
fork_scope 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 fork_scope 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 fork_scope. 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.
fork_scope is provided by the Nocturnusai MCP server (nocturnusai-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 16 Nocturnusai tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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