AllowanceGuard

Deterministic pre-approval allowance checks for Base agents, paid per call.

AllowanceGuard answers one question before an agent signs an irreversible approve: should this spender get this allowance. It reads the allowance the spender already holds, classifies the one being requested against the token's own supply rather than a list of sentinel values, and says whether signing raises or lowers exposure — so reducing an unlimited allowance is recognised as safer than the status quo instead of flagged as another approval. It checks whether the spender is a contract at all, whether its code can be swapped after the grant, and whether it is on the denylist. There is no model anywhere in it. When a fact cannot be read the answer is unknown, never a quiet allow.

Endpoints

RouteWhat it doesPrice
POST /v1/guard/allowanceDecide whether to grant a token allowance before signing the approve$0.015

Call it

Send the request unpaid to see the live quote. You get HTTP 402 and a PAYMENT-REQUIRED header.

curl -i -sS -X POST https://allowance.schemasure.com/v1/guard/allowance \
  -H 'content-type: application/json' \
  -d '{"calldata":{"from":"0x9F2C5E4A8db1C3a7E6B0d4f8C1E2a5b7D9C0e3F4","to":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","data":"0x095ea7b30000000000000000000000002626664c2603336e57b271c5c0b26f421741e4810000000000000000000000000000000000000000000000000000000000000000"}}'

Payment

Honest uncertainty

Every response carries a verdict. When this service cannot determine an answer it returns unknown with evidence explaining why. It never reports an undetermined result as a clean one.

For agents