Scans trending markets on both Polymarket and Kalshi simultaneously, matches markets covering the same underlying question, and surfaces pairs where implied probabilities diverge by more than a threshold. A divergence of 5pp or more suggests one exchange is mispriced or lagging. Returns pairs ran...
Part of the Syenite server.
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AI agents call prediction.arbitrage to retrieve information from Syenite 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 prediction.arbitrage 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": {
"prediction.arbitrage": {}
}
}See the full Syenite policy for all 46 tools.
These attack patterns abuse exactly the kind of access prediction.arbitrage 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.
Scans trending markets on both Polymarket and Kalshi simultaneously, matches markets covering the same underlying question, and surfaces pairs where implied probabilities diverge by more than a threshold. A divergence of 5pp or more suggests one exchange is mispriced or lagging. Returns pairs ranked by divergence, each showing the YES probability on each exchange, which side is higher, and the spread in percentage points. Optionally pass minDivergencePp (default 3) to filter only meaningful gaps, and limit (default 20, max 50). Note: cross-exchange arb requires accounts on both platforms and faces execution risk — prices may converge before orders fill.. It is categorised as a Read tool in the Syenite MCP Server, which means it retrieves data without modifying state.
Register the Syenite MCP server in PolicyLayer and add a rule for prediction.arbitrage: 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 Syenite. Nothing to install.
prediction.arbitrage 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 prediction.arbitrage 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 prediction.arbitrage. 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.
prediction.arbitrage is provided by the Syenite MCP server (@syenite/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 46 Syenite tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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