Find arbitrage opportunities on Polymarket via monotonicity violations + partition-sum checks. TWO MODES: (1) event — pass a single Polymarket event slug; walks child markets, checks date-axis / threshold-axis ordering AND computes the partition_check (sum of YES prices across mutually-exclusive ...
Part of the Lichess server.
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AI agents call polymarket_arbitrage to retrieve information from Lichess 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 polymarket_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": {
"polymarket_arbitrage": {}
}
}See the full Lichess policy for all 30 tools.
These attack patterns abuse exactly the kind of access polymarket_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.
Find arbitrage opportunities on Polymarket via monotonicity violations + partition-sum checks. TWO MODES: (1) event — pass a single Polymarket event slug; walks child markets, checks date-axis / threshold-axis ordering AND computes the partition_check (sum of YES prices across mutually-exclusive legs — should ≈1; deviations >3pp emit a BUY/SELL EVERY LEG signal). (2) topic — pass a seed question ("Strait of Hormuz traffic returns to normal"); searches related events across the platform, flattens markets, runs the comparator on the union. Cross-event mode catches "...by May 31" vs "...by Jun 30" patterns that single-event misses. SEMANTIC ANCHOR: cross-event pairs require ≥0.30 Jaccard similarity on question tokens (prevents Powell-Fed-Pause being paired with Powell-DOJ-probe); skipped_low_similarity surfaces the rejected pair count. PARTITION FILTER: drops will-person-X / will-manager-Y / will-someone-else- placeholder slugs; partitions with >20% placeholder fraction return null arb signal. Response: opportunities[] (gap_pp, suggested_trade, reasoning, monotonicity violation context), and in event mode partition_check{sum_yes_prices, gap_from_1, placeholders_filtered, suggested_trade}.. It is categorised as a Read tool in the Lichess MCP Server, which means it retrieves data without modifying state.
Register the Lichess MCP server in PolicyLayer and add a rule for polymarket_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 Lichess. Nothing to install.
polymarket_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 polymarket_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 polymarket_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.
polymarket_arbitrage is provided by the Lichess MCP server (https://gateway.pipeworx.io/lichess/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 30 Lichess tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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