NEXUS Data Validation

Intelligent data quality checks and schema validation

Security Scan

The skill is internally coherent: it is an instruction-only wrapper for a paid external NEXUS data-validation API and only requests a single payment-proof credential; there are no install steps or unrelated permissions, but you should treat the payment credential and any signed Stellar XDR as sensitive and verify the external service before use.

Purpose & Capability

Name/description (data quality + schema validation) matches the SKILL.md and README: the skill forwards input to an external NEXUS data-validation API. The declared requirement (a payment-proof credential) aligns with the documented paywalled API behavior. Nothing required (binaries/config paths) is unrelated to the stated purpose.

Instruction Scope

The SKILL.md instructs the agent to POST inputs to a remote endpoint and to follow several payment flows (x402, MPP, legacy X-Payment-Proof). It does not direct filesystem access or shell execution. It does require contacting third-party endpoints (ai-service-hub-15.emergent.host) and, in the Stellar sponsorship flow, posting signed XDRs — which could reveal transaction details. These network actions are consistent with a paid external API but mean your data (and potentially payment metadata) will leave the agent.

Install Mechanism

No install spec and no code files — this is instruction-only. That minimizes local write/execution risk. There is no downloading of arbitrary archives or external installers.

Credentials

The skill requires a single environment variable: NEXUS_PAYMENT_PROOF (declared as primaryEnv). That is proportionate for a paywalled API. However, this value is a sensitive payment credential; users should ensure they do not store private keys or account secrets there. The SKILL.md also encourages posting signed Stellar XDRs to a sponsor endpoint — this is not expressed as an env var requirement but is sensitive operationally.

Persistence & Privilege

always is false and the skill is user-invocable; disable-model-invocation is false (normal). The skill does not request persistent installation-wide privileges or attempt to modify other skills or system config. Note: because the agent may invoke the skill autonomously, it could make paid requests if triggered — ensure you control invocation policies if unwanted charges are a concern.

Assessment

This skill is a thin wrapper around a paid third-party API (ai-service-hub-15.emergent.host). Before installing: 1) Confirm you trust that domain and review its documentation. 2) Use the sandbox_test mode to verify behavior without payment. 3) Treat NEXUS_PAYMENT_PROOF as a secret — do not place private keys or wallet seeds there. 4) Be cautious about submitting signed Stellar XDRs to the sponsor endpoint (they may reveal transaction metadata). 5) If you want to avoid accidental charges, restrict autonomous invocation or require manual approval for any payment flow. If any of the above is unacceptable or the service/provider is unfamiliar, do not install.

Data Validation API

NEXUS Agent-as-a-Service on Cardano + Stellar | Price: $0.18/request | Accepts: ADA, DJED, iUSD, USDCx, USDM (Cardano) + USDC, XLM (Stellar)

When to use

Use when you need to intelligent data quality checks and schema validation.

Steps

Option A: x402 Standard (Recommended)

1. Call the service endpoint without payment headers.
2. Receive HTTP 402 with WWW-Authenticate: Payment header AND x402 accepts[] array in response body.
3. Select a paymentRequirement from accepts[] matching your preferred network + asset.
4. Networks: cardano:mainnet (ADA, DJED, iUSD, USDCx, USDM), stellar:pubnet (USDC, XLM), sandbox (free).
5. Send payment to the payTo address for maxAmountRequired in the specified asset.
6. Stellar fee sponsorship: POST your signed XDR to https://ai-service-hub-15.emergent.host/api/mpp/stellar/sponsor — NEXUS pays gas, you need 0 XLM.
7. Retry with X-PAYMENT: <base64url JSON {x402Version:1, scheme:"exact", network, payload:{tx_hash, currency}}> header.
8. Parse the JSON response and X-PAYMENT-RESPONSE header.

Option B: MPP Standard

1. Call the service endpoint without payment headers.
2. Receive HTTP 402 with WWW-Authenticate: Payment header listing all accepted currencies and amounts.
3. Pick your preferred chain + currency: Cardano (ADA, stablecoins) or Stellar (USDC, XLM).
4. Create payment: Masumi escrow (Cardano) or direct Stellar transfer.
5. Stellar fee sponsorship: POST your signed XDR to https://ai-service-hub-15.emergent.host/api/mpp/stellar/sponsor — NEXUS pays gas, you need 0 XLM.
6. Retry with Authorization: Payment <base64url-credential> header.
7. Parse the JSON response and Payment-Receipt header.

Option C: Legacy Header

1. Send a POST request to the NEXUS API endpoint with your input.
2. Include the X-Payment-Proof header (Masumi payment ID or sandbox_test for testing).
3. Parse the JSON response and return the result.

API Call

curl -X POST https://ai-service-hub-15.emergent.host/api/original-services/data-validation \
  -H "Content-Type: application/json" \
  -H "X-Payment-Proof: $NEXUS_PAYMENT_PROOF" \
  -d '{
  "input": "Example input for Data Validation API"
}'

Endpoint: https://ai-service-hub-15.emergent.host/api/original-services/data-validation Method: POST Headers:

• Content-Type: application/json
• X-PAYMENT: <base64url JSON> (x402 standard — recommended)
• Authorization: Payment <credential> (MPP standard)
• X-Payment-Proof: <masumi_payment_id> (legacy — use sandbox_test for free testing)

Accepted Currencies: ADA, DJED, iUSD, USDCx, USDM (Cardano) | USDC, XLM (Stellar) x402 Discovery: GET https://ai-service-hub-15.emergent.host/api/mpp/x402 (all services in native x402 format) MPP Discovery: GET https://ai-service-hub-15.emergent.host/api/mpp/discover Stablecoin Registry: GET https://ai-service-hub-15.emergent.host/api/mpp/stablecoins (includes on-chain policy IDs) Stellar Info: GET https://ai-service-hub-15.emergent.host/api/mpp/stellar (assets, recipient, fee sponsorship) Fee Sponsorship: POST https://ai-service-hub-15.emergent.host/api/mpp/stellar/sponsor (NEXUS pays Stellar gas — agents need 0 XLM)

External Endpoints

URL	Method	Data Sent
https://ai-service-hub-15.emergent.host/api/original-services/data-validation	POST	Input parameters as JSON body

Security & Privacy

• All data is sent to https://ai-service-hub-15.emergent.host over HTTPS/TLS.
• No data is stored permanently; requests are processed and discarded.
• Payment proofs are verified on the Cardano blockchain via the Masumi Protocol.
• No filesystem access or shell execution required.

Model Invocation Note

This skill calls the NEXUS AI service API which uses LLM models (GPT-5.2, Claude Sonnet 4.5, GPT-4o) to process requests. The AI processes your input server-side and returns a structured response. You may opt out by not installing this skill.

Trust Statement

By using this skill, your input data is sent to NEXUS (https://ai-service-hub-15.emergent.host) for AI processing. Payments are non-custodial via the Masumi Protocol on Cardano. Only install if you trust NEXUS as a service provider. Visit https://ai-service-hub-15.emergent.host for full documentation.

Tags

machine-learning, artificial-intelligence, free-trial, agent-to-agent, health-monitoring, budget