clause.

Are these two the same bet?

You are about to trade a spread between two contracts that resolve differently, and nothing you own will tell you. Name two tracked contracts and Clause compares the rule sets field by field, then says which field blocks the match.

A market_key, or a fragment of the title. A Polymarket slug is neither and will not match.

Comparing the two contracts in the example below.

The worked example

The failure

One clause, two different bets

Polymarket and Kalshi both list a market on US AI regulation. Every cross-venue screen shows them as one market at a spread.

Polymarket resolves YES only on a restrictive provision: a prohibition, a training restriction, a human-in-the-loop requirement. Kalshi resolves YES on a federal framework “regardless of whether those provisions mandate private-sector compliance or promote voluntary guidelines.”

A voluntary standards act resolves one YES and the other NO. Anyone holding both as a hedge holds two positions and believes they hold none.

One clause, found by reading both rule sets in full.

The rule

Silence is not agreement

That divergence exists as an explicit clause on one side matched by silence on the other. Kalshi says what it does with voluntary measures; Polymarket says nothing.

Any comparator that reads an absent field as agreement is broken. So an unknown on a material field produces REVIEW_REQUIRED, never a pass.

The asymmetry is deliberate. A false negative costs a missed trade; a false positive costs the position.

The best verdict this returns is LIKELY_EQUIVALENT, and it carries the clauses to read. It never returns EQUIVALENT: a regex has not read the statute.

We went looking for a true cross-venue match and did not find one

6,453 candidate pairs, across 113 Polymarket and 117,228 Kalshi markets. Not one could be confirmed as the same bet. The closest six differ on who decides: media consensus on one side, inauguration on the other.

That is a negative result and we publish it as one. It is also the point: the spreads people trade across these venues sit between contracts nobody has read side by side.

This page is one call to /v1/mcp-equivalence, which takes identifiers. /v1/equivalence takes the two rule texts directly. Read the API → The comparison is structural, not a legal opinion.