Show your current plan usage and remaining limits. Displays how many agents, test generations, simulation runs, and API keys you've used this month vs your plan limits. WHEN TO USE: Before Phase 2 (test generation) to check if the user has enough quota. Also useful when the user asks about their ...
Part of the Invarium server.
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AI agents call invarium_usage to retrieve information from Invarium 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 invarium_usage 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": {
"invarium_usage": {}
}
}See the full Invarium policy for all 19 tools.
These attack patterns abuse exactly the kind of access invarium_usage 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.
Show your current plan usage and remaining limits. Displays how many agents, test generations, simulation runs, and API keys you've used this month vs your plan limits. WHEN TO USE: Before Phase 2 (test generation) to check if the user has enough quota. Also useful when the user asks about their plan or limits. The generate_tests tool checks this automatically, but showing it to the user proactively helps them plan their testing budget. No parameters required. Returns usage for the authenticated user.. It is categorised as a Read tool in the Invarium MCP Server, which means it retrieves data without modifying state.
Register the Invarium MCP server in PolicyLayer and add a rule for invarium_usage: 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 Invarium. Nothing to install.
invarium_usage 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 invarium_usage 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 invarium_usage. 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.
invarium_usage is provided by the Invarium MCP server (invarium-ai/invarium). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 19 Invarium tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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