Get historical constraints for a task
Part of the Cairn server.
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AI agents use cairn_plan to create or modify resources in Cairn. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call cairn_plan repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Cairn.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"cairn_plan": {
"limits": [
{
"counter": "cairn_plan_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Cairn policy for all 16 tools.
These attack patterns abuse exactly the kind of access cairn_plan gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Get historical constraints for a task. It is categorised as a Write tool in the Cairn MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Cairn MCP server in PolicyLayer and add a rule for cairn_plan: 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 Cairn. Nothing to install.
cairn_plan is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the cairn_plan 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 cairn_plan. 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.
cairn_plan is provided by the Cairn MCP server (cairn-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 16 Cairn tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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4,600+ MCP servers and 31,000+ tools scanned and risk-classified.