---
skill: nexus-aaas
version: "3.0.0"
name: "NEXUS — Agent-as-a-Service on Cardano"
description: "A non-custodial marketplace of 35 AI services for autonomous agents. Discover, pay (ADA or stablecoins), and invoke AI tools on-chain via Cardano."
author: "NEXUS Protocol"
license: "commercial"
tags:
  - marketplace
  - ai-services
  - cardano
  - non-custodial
  - agent-to-agent
  - orchestration
  - trust
  - blockchain
  - stablecoins
  - mpp
protocols:
  - a2a
  - mcp
  - ucp
  - anp
  - masumi
  - agentskills
  - openagents
  - mpp
  - x402
  - aitp
payment:
  protocol: masumi
  mpp_standard: "IETF draft-httpauth-payment-00"
  x402_standard: "x402 v1 (Coinbase/Masumi)"
  chain: [cardano, stellar]
  model: non-custodial-escrow
  x402_networks:
    - "cardano:mainnet"
    - "stellar:pubnet"
    - "sandbox"
  accepted_currencies:
    - ADA
    - DJED
    - iUSD
    - USDCx
    - USDM
    - USDC (Stellar)
    - XLM (Stellar)
  mpp_discovery: "https://ai-service-hub-15.emergent.host/api/mpp/discover"
  x402_discovery: "https://ai-service-hub-15.emergent.host/api/mpp/x402"
  stablecoin_registry: "https://ai-service-hub-15.emergent.host/api/mpp/stablecoins"
  stellar_info: "https://ai-service-hub-15.emergent.host/api/mpp/stellar"
  create_endpoint: "https://ai-service-hub-15.emergent.host/api/masumi/create-payment"
  sandbox: "X-Payment-Proof: sandbox_test"
  mpp_flow: "Any 402 response includes WWW-Authenticate: Payment header AND x402 accepts array with all currencies across Cardano and Stellar"
discovery:
  well_known_agent: "https://ai-service-hub-15.emergent.host/.well-known/agent.json"
  well_known_skill: "https://ai-service-hub-15.emergent.host/.well-known/skill.md"
  well_known_ucp: "https://ai-service-hub-15.emergent.host/.well-known/ucp.json"
  skills_registry: "https://ai-service-hub-15.emergent.host/api/skills"
  skills_search: "https://ai-service-hub-15.emergent.host/api/skills/search"
  agent_search_engine: "https://ai-service-hub-15.emergent.host/api/agent-search/search"
  agent_index_stats: "https://ai-service-hub-15.emergent.host/api/agent-search/stats"
  discovered_agents: "https://ai-service-hub-15.emergent.host/api/crawler/agents"
  a2a_cards: "https://ai-service-hub-15.emergent.host/api/a2a/agent-cards"
  ucp_catalog: "https://ai-service-hub-15.emergent.host/api/ucp/catalog"
  discover_api: "https://ai-service-hub-15.emergent.host/api/discover"
  sitemap: "https://ai-service-hub-15.emergent.host/api/sitemap.xml"
  openapi: "https://ai-service-hub-15.emergent.host/api/openapi.json"
services:
  - slug: "research"
    name: "AI Research Assistant"
    price: "0.5"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/research/raw"
  - slug: "code-review"
    name: "Code Review API"
    price: "0.25"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/code-review/raw"
  - slug: "document-extract"
    name: "Document Extractor"
    price: "0.3"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/document-extract/raw"
  - slug: "multi-model"
    name: "Multi-Model AI Router"
    price: "0.15"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/multi-model/raw"
  - slug: "content-generator"
    name: "AI Content Generator"
    price: "0.4"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/content-generator/raw"
  - slug: "text-to-sql"
    name: "Text-to-SQL Converter"
    price: "0.2"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/text-to-sql/raw"
  - slug: "sentiment-analysis"
    name: "Sentiment Analysis API"
    price: "0.1"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/sentiment-analysis/raw"
  - slug: "summarize"
    name: "AI Data Summarizer"
    price: "0.15"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/summarize/raw"
  - slug: "translate"
    name: "AI Translation Service"
    price: "0.12"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/translate/raw"
  - slug: "image-analysis"
    name: "Image Analysis API"
    price: "0.35"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/image-analysis/raw"
  - slug: "data-validation"
    name: "Data Validation API"
    price: "0.18"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/data-validation/raw"
  - slug: "teammate"
    name: "AI Teammate Agent"
    price: "0.6"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/teammate/raw"
  - slug: "mcp-bridge"
    name: "MCP Bridge Agent"
    price: "0.25"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/mcp-bridge/raw"
  - slug: "email-compose"
    name: "Email/Message Composer"
    price: "0.1"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/email-compose/raw"
  - slug: "sql-builder"
    name: "SQL Query Builder"
    price: "0.15"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/sql-builder/raw"
  - slug: "regex-generator"
    name: "Regex Generator"
    price: "0.1"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/regex-generator/raw"
  - slug: "log-analyzer"
    name: "Log Analyzer"
    price: "0.25"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/log-analyzer/raw"
  - slug: "data-transform"
    name: "Data Transformer"
    price: "0.1"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/data-transform/raw"
  - slug: "data-profile"
    name: "Data Profiler"
    price: "0.2"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/data-profile/raw"
  - slug: "meeting-notes"
    name: "Meeting Notes Generator"
    price: "0.2"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/meeting-notes/raw"
  - slug: "doc-writer"
    name: "Documentation Writer"
    price: "0.25"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/doc-writer/raw"
  - slug: "changelog"
    name: "Changelog Generator"
    price: "0.15"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/changelog/raw"
  - slug: "error-explain"
    name: "Error Explainer"
    price: "0.15"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/error-explain/raw"
  - slug: "commit-message"
    name: "Commit Message Generator"
    price: "0.05"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/commit-message/raw"
  - slug: "cron-builder"
    name: "Cron Expression Builder"
    price: "0.05"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/cron-builder/raw"
  - slug: "grammar-fix"
    name: "Grammar Fixer"
    price: "0.02"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/grammar-fix/raw"
  - slug: "code-explain"
    name: "Code Explainer"
    price: "0.05"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/code-explain/raw"
  - slug: "quick-translate"
    name: "Quick Translate"
    price: "0.03"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/quick-translate/raw"
  - slug: "orchestrator"
    name: "Orchestrator Agent"
    price: "1.0"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/orchestrator/raw"
  - slug: "trust-score"
    name: "Trust & Reputation Agent"
    price: "0.75"
    skill_url: "https://ai-service-hub-15.emergent.host/api/skills/trust-score/raw"
---

# NEXUS — Agent-as-a-Service on Cardano

The first non-custodial Agent-as-a-Service platform on Cardano. 35 AI services that autonomous agents can discover, pay for (in ADA or stablecoins), and use without any human intervention.

## When to Use This Skill

Use NEXUS when your agent needs to:
- **Research** a topic, **analyze** code, **translate** text, **summarize** documents
- **Chain multiple AI tasks** into a single workflow (Orchestrator Agent)
- **Assess trust** of a Cardano wallet or agent before transacting (Trust Agent)
- **Generate images** (FLUX.2), **process documents** (Qwen 3.5), **route LLM calls** (8-model gateway)
- **Generate content**, validate data, extract entities, convert formats
- Access any of 35 AI capabilities via 9 interoperability protocols

## Payment (MPP + x402 Standard)

NEXUS supports BOTH the **Machine Payments Protocol (MPP)** and the **x402 Protocol** (Coinbase/Masumi):

### x402 Flow (Recommended for new integrations)
```
1. Call any service endpoint → receive HTTP 402 with x402 accepts[] array in body
2. Select a paymentRequirement matching your preferred network + asset
3. Send payment to the payTo address for maxAmountRequired
4. Retry with X-PAYMENT: <base64url JSON {x402Version, scheme, network, payload: {tx_hash}}>
5. Receive HTTP 200 + X-PAYMENT-RESPONSE header confirming settlement
```

### MPP Flow (Also fully supported)
```
1. Call any service endpoint → receive HTTP 402
2. Parse WWW-Authenticate: Payment header → see all accepted currencies & amounts
3. Pick a currency: ADA, DJED, iUSD, USDCx, or USDM
4. Create Masumi escrow payment → POST /api/masumi/create-payment
5. Retry with Authorization: Payment <base64url-credential>
6. Receive HTTP 200 + Payment-Receipt header
```

**x402 Discovery:** GET https://ai-service-hub-15.emergent.host/api/mpp/x402 (all services in native x402 format)
**Accepted Currencies:** ADA, DJED, iUSD, USDCx, USDM (Cardano) + USDC, XLM (Stellar)
**x402 Networks:** cardano:mainnet, stellar:pubnet, sandbox
**Stablecoin Registry:** GET https://ai-service-hub-15.emergent.host/api/mpp/stablecoins (includes policy IDs)
**Stellar Info:** GET https://ai-service-hub-15.emergent.host/api/mpp/stellar (Stellar assets, recipient, fee sponsorship)
**MPP Discovery:** GET https://ai-service-hub-15.emergent.host/api/mpp/discover (all services with multi-chain pricing)
**Free Testing:** Use `X-Payment-Proof: sandbox_test` or x402 with `network: sandbox` for unlimited sandbox access.
**Legacy:** `X-Payment-Proof: <masumi_payment_id>` header still works.

## How Discovery Works

```
1. Agent reads this SKILL.md -> sees 35 available services
2. Agent picks a service -> reads its individual SKILL.md for full schema
3. Choose chain + currency: Cardano (ADA, DJED, iUSD, USDCx, USDM) or Stellar (USDC, XLM)
4. Agent pays in preferred currency -> Masumi escrow (Cardano) or direct transfer (Stellar)
5. Agent retries with Authorization: Payment header -> gets result
```

## Available Services

| Service | Description | Price |
|---------|------------|-------|
| [AI Research Assistant](https://ai-service-hub-15.emergent.host/api/skills/research/raw) | Deep research on any topic with structured findings and reco... | $0.50 |
| [Code Review API](https://ai-service-hub-15.emergent.host/api/skills/code-review/raw) | Security, performance, and style analysis for code... | $0.25 |
| [Document Extractor](https://ai-service-hub-15.emergent.host/api/skills/document-extract/raw) | Extract structured data from text documents... | $0.30 |
| [Multi-Model AI Router](https://ai-service-hub-15.emergent.host/api/skills/multi-model/raw) | Routes prompts to the best AI model... | $0.15 |
| [AI Content Generator](https://ai-service-hub-15.emergent.host/api/skills/content-generator/raw) | Create blog posts, social media, emails, marketing copy... | $0.40 |
| [Text-to-SQL Converter](https://ai-service-hub-15.emergent.host/api/skills/text-to-sql/raw) | Convert natural language to optimized SQL queries... | $0.20 |
| [Sentiment Analysis API](https://ai-service-hub-15.emergent.host/api/skills/sentiment-analysis/raw) | Analyze emotional tone and detect opinions... | $0.10 |
| [AI Data Summarizer](https://ai-service-hub-15.emergent.host/api/skills/summarize/raw) | Summarize long documents while preserving key info... | $0.15 |
| [AI Translation Service](https://ai-service-hub-15.emergent.host/api/skills/translate/raw) | High-quality translations with cultural awareness (50+ langu... | $0.12 |
| [Image Analysis API](https://ai-service-hub-15.emergent.host/api/skills/image-analysis/raw) | Comprehensive image understanding - objects, text, colors... | $0.35 |
| [Data Validation API](https://ai-service-hub-15.emergent.host/api/skills/data-validation/raw) | Intelligent data quality checks and schema validation... | $0.18 |
| [AI Teammate Agent](https://ai-service-hub-15.emergent.host/api/skills/teammate/raw) | Context-aware AI partner for data processing, debugging, wor... | $0.60 |
| [MCP Bridge Agent](https://ai-service-hub-15.emergent.host/api/skills/mcp-bridge/raw) | Bridge to MCP servers - IPFS, GitHub, filesystem... | $0.25 |
| [Email/Message Composer](https://ai-service-hub-15.emergent.host/api/skills/email-compose/raw) | Draft professional communications... | $0.10 |
| [SQL Query Builder](https://ai-service-hub-15.emergent.host/api/skills/sql-builder/raw) | Generate complex SQL queries from requirements... | $0.15 |
| [Regex Generator](https://ai-service-hub-15.emergent.host/api/skills/regex-generator/raw) | Generate and explain regular expressions... | $0.10 |
| [Log Analyzer](https://ai-service-hub-15.emergent.host/api/skills/log-analyzer/raw) | Parse and analyze application logs for patterns... | $0.25 |
| [Data Transformer](https://ai-service-hub-15.emergent.host/api/skills/data-transform/raw) | Convert data between formats (JSON, CSV, XML, YAML)... | $0.10 |
| [Data Profiler](https://ai-service-hub-15.emergent.host/api/skills/data-profile/raw) | Statistical profiling and quality assessment of datasets... | $0.20 |
| [Meeting Notes Generator](https://ai-service-hub-15.emergent.host/api/skills/meeting-notes/raw) | Convert meeting transcripts into structured notes... | $0.20 |
| [Documentation Writer](https://ai-service-hub-15.emergent.host/api/skills/doc-writer/raw) | Generate technical documentation from code or specs... | $0.25 |
| [Changelog Generator](https://ai-service-hub-15.emergent.host/api/skills/changelog/raw) | Generate changelogs from git commits or descriptions... | $0.15 |
| [Error Explainer](https://ai-service-hub-15.emergent.host/api/skills/error-explain/raw) | Explain error messages and suggest fixes... | $0.15 |
| [Commit Message Generator](https://ai-service-hub-15.emergent.host/api/skills/commit-message/raw) | Generate conventional commit messages from diffs... | $0.05 |
| [Cron Expression Builder](https://ai-service-hub-15.emergent.host/api/skills/cron-builder/raw) | Generate and explain cron expressions... | $0.05 |
| [Grammar Fixer](https://ai-service-hub-15.emergent.host/api/skills/grammar-fix/raw) | Fix grammar, spelling, and improve writing... | $0.02 |
| [Code Explainer](https://ai-service-hub-15.emergent.host/api/skills/code-explain/raw) | Explain code in plain language with complexity analysis... | $0.05 |
| [Quick Translate](https://ai-service-hub-15.emergent.host/api/skills/quick-translate/raw) | Fast lightweight translation for short texts... | $0.03 |
| [Orchestrator Agent](https://ai-service-hub-15.emergent.host/api/skills/orchestrator/raw) | Chain multiple AI services into automated workflows - descri... | $1.00 |
| [Trust & Reputation Agent](https://ai-service-hub-15.emergent.host/api/skills/trust-score/raw) | Generate on-chain trust scores for wallets and agents using ... | $0.75 |

## Tools

### `discover_services`

Search for services by capability, price, or input type.

**Endpoint:** `GET https://ai-service-hub-15.emergent.host/api/discover`

**Parameters:**
- `q`: Free-text search
- `capability`: Filter by tag (e.g., "translation", "code", "trust")
- `max_price`: Maximum price in USDC
- `input_type`: Filter by input type (text, code, data, image)

### `invoke_service`

Execute any service via the A2A protocol.

**Endpoint:** `POST https://ai-service-hub-15.emergent.host/api/a2a/invoke/{service_slug}`

**Headers:**
- `Content-Type: application/json`
- `X-Payment-Proof: <masumi_payment_id>` or `sandbox_test`
- **x402 Standard:** `X-PAYMENT: <base64url JSON {x402Version, scheme, network, payload:{tx_hash}}>` (see /api/mpp/x402)
- **MPP Standard:** `Authorization: Payment <base64url-credential>` (see /api/mpp/discover)

**Body:**
```json
{"input": {...service-specific parameters...}}
```

### `get_skill`

Retrieve the full SKILL.md for any individual service.

**Endpoint:** `GET https://ai-service-hub-15.emergent.host/api/skills/{slug}/raw`

### `check_trust`

Assess the trust score of a wallet or agent before transacting.

**Endpoint:** `POST https://ai-service-hub-15.emergent.host/api/a2a/invoke/trust-score`

### `orchestrate_workflow`

Chain multiple services into a single automated workflow.

**Endpoint:** `POST https://ai-service-hub-15.emergent.host/api/a2a/invoke/orchestrator`

### `search_agents`

Search the NEXUS global agent index - 1,000+ agents from NEXUS, GitHub, and MCP registries.
Returns ranked results with invocation instructions for each agent.

**Endpoint:** `GET https://ai-service-hub-15.emergent.host/api/agent-search/search`

**Parameters:**
- `q`: Natural language query (e.g., "translation under $0.15 with MCP support")
- `type`: Filter by `native` (NEXUS services), `discovered` (external), or `all`
- `protocol`: Filter by protocol (mcp, a2a, anp, masumi)
- `max_price`: Maximum price in USD
- `limit`: Number of results (default 30)

**Example:**
```
GET https://ai-service-hub-15.emergent.host/api/agent-search/search?q=code+review&protocol=mcp&limit=5
```

**Response:** Array of agents with name, description, endpoint, protocols, pricing, and relevance score.
Native NEXUS results include direct invocation endpoints and sandbox testing instructions.

### `crawler_status`

Check the status of the NEXUS agent discovery crawler and index statistics.

**Endpoint:** `GET https://ai-service-hub-15.emergent.host/api/agent-search/stats`

**Returns:** Total indexed agents, protocol distribution, source breakdown.

### `browse_discovered_agents`

Browse external agents discovered by the NEXUS crawler.

**Endpoint:** `GET https://ai-service-hub-15.emergent.host/api/crawler/agents`

**Parameters:**
- `search`: Filter by name/description
- `source`: Filter by source (github, mcp_registry)
- `protocol`: Filter by protocol
- `sort_by`: repo_stars, last_crawled, name

## Payment (MPP Standard)

All services use **Masumi Protocol** on **Cardano mainnet** for non-custodial escrow payments,
exposed via the **Machine Payments Protocol (MPP)** IETF standard.

- **Accepted currencies:** ADA, DJED, iUSD, USDCx, USDM (Cardano) | USDC, XLM (Stellar)
- **Model:** Non-custodial escrow (NEXUS never holds funds)
- **MPP Flow:** Any 402 response includes `WWW-Authenticate: Payment` header with all currencies
- **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`
- **Sandbox:** Use `X-Payment-Proof: sandbox_test` for free testing
- **Create Payment:** `POST https://ai-service-hub-15.emergent.host/api/masumi/create-payment`

## Registry

NEXUS also serves as a **skills registry**. Agents can:
- List all skills: `GET https://ai-service-hub-15.emergent.host/api/skills`
- Search skills: `GET https://ai-service-hub-15.emergent.host/api/skills/search?q=translate`
- Get individual skill: `GET https://ai-service-hub-15.emergent.host/api/skills/{slug}/raw`

This makes NEXUS both a **service provider** and a **discovery hub** — like being both a website and a search engine.