Use this service when you need this capability: compute the standard EIP-191 personal-message hash for supplied text or bytes.
0.005 USDC per call
x402 V2 exact payment on Base mainnet (eip155:8453) using USDC. The HTTP 402 challenge confirms the exact requirements before an authorized payment.
POST https://signalharness.ai/api/agent/services/message_hash_eip191/invokeCompute the standard EIP-191 personal-message hash for supplied text or bytes.
Caller-supplied data is processed deterministically. These tools do not supply live market feeds, query blockchain RPC, host AI models, or verify that supplied history is complete. Payment remains Base USDC for every chain category.
| Field | Type | Required | Limits |
|---|---|---|---|
| message_hash_request | string | Required | Minimum length 2; Maximum length 65536 |
{
"message_hash_request": "{\"message\":\"SignalHarness public test vector\",\"encoding\":\"utf8\"}"
}{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"additionalProperties": false,
"minProperties": 1,
"maxProperties": 1,
"required": [
"message_hash_request"
],
"properties": {
"message_hash_request": {
"type": "string",
"minLength": 2,
"maxLength": 65536
}
}
}Illustrative output from the canonical adapter fixture and schema. It is not a completed paid execution or a current live observation.
{
"service_id": "message_hash_eip191",
"evidence_scope": "caller_supplied_data",
"message_hash": "{\"encoding\":\"utf8\",\"hash\":\"0x43c3ce76740c0da4b23274e62f830220acfc4cb8d66dc3c373c6f58db8620442\"}",
"warnings": [
"Hashing does not sign or prove authorship."
]
}{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"additionalProperties": false,
"minProperties": 4,
"maxProperties": 4,
"required": [
"service_id",
"evidence_scope",
"message_hash",
"warnings"
],
"properties": {
"service_id": {
"type": "string",
"const": "message_hash_eip191",
"minLength": 19,
"maxLength": 19
},
"evidence_scope": {
"type": "string",
"const": "caller_supplied_data",
"minLength": 20,
"maxLength": 20
},
"message_hash": {
"type": "string",
"minLength": 1,
"maxLength": 65536
},
"warnings": {
"type": "array",
"minItems": 1,
"maxItems": 8,
"items": {
"type": "string",
"minLength": 1,
"maxLength": 512
}
}
}
}Timeout: 5000 ms. Full schemas are in OpenAPI.
This schema-valid request returns the canonical HTTP 402 challenge without executing the service. A payment-capable client validates the challenge, signs only with prior authority and budget, and retries the identical body.
curl -i -X POST https://signalharness.ai/api/agent/services/message_hash_eip191/invoke \
-H "Content-Type: application/json" \
--data '{"message_hash_request":"{\"message\":\"SignalHarness public test vector\",\"encoding\":\"utf8\"}"}'