vonmises_variate
AI agents call vonmises_variate to retrieve information from FortunaMCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Von Mises variates are mathematical distributions used to generate random numbers. This tool reads from an internal RNG state and returns computed values without side effects, external operations, or data mutation. While not a traditional 'Read' operation (which typically queries external data), it is the closest fit as it retrieves/computes values without modification or execution of arbitrary code.
From the tool's definition Tool name 'vonmises_variate' indicates a Von Mises random variate generator, consistent with sibling tools (bernoulli_variate, beta_variate, etc.) that are all random value generators.
Attacks that exploit this kind of access
vonmises_variate. It is categorised as a Read tool in the FortunaMCP MCP Server, which means it retrieves data without modifying state.
Register the Fortuna MCP server in PolicyLayer and add a rule for vonmises_variate: 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 FortunaMCP. Nothing to install.
vonmises_variate 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 vonmises_variate 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 vonmises_variate. 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.
vonmises_variate is provided by the Fortuna MCP server (siliconsociety/fortunamcp). 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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