Relay MCP Server
An AI operations agent that reads from your own PostgreSQL database and policy documents, provides grounded answers with citations, and exposes read-only tools to external MCP clients while keeping writes behind a human approval gate.
README
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Relay
An AI operations agent that answers from your own data, cites your own policies, and stops for a human before it spends a cent.
1 orchestrator · 2 specialists · 9 tools · 1 human-gated write
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Operations teams live in a gap. The answer to "why hasn't this customer's order arrived, and do we owe them money?" sits in two places at once: the order database, and a policy document nobody has read since onboarding. Closing that gap by hand is most of what a support agent does all day.
Relay closes it — and shows its work while it does.

What makes this different from a chatbot
It reads your systems, not the internet. Nine tools query a live PostgreSQL database. The model is forbidden from stating any fact that did not come from a tool result, and every call is visible on screen with its real latency.
It renders product, not prose. Ask what is running late and you get a table with status badges and days late. Ask for an overview and you get a dashboard. The model chooses the tool; the frontend owns how the result looks, so the output is always well-formed no matter what the model does.
It cites your policies. Upload a PDF and it is chunked, embedded and searchable in seconds. Retrieval is hybrid — vector similarity for meaning, Postgres full-text for exact terms like an SKU — fused with reciprocal rank. Embeddings are computed in-process, so document contents never leave your server.
It cannot spend your money. Exactly one tool writes. It sits on the orchestrator, behind a human approval gate, capped at the order total and idempotent. No specialist can move money, and no amount of delegation can route around the gate. That is a property of the topology, not a setting.
It plugs into what you already use. Relay is also an MCP server. Point Claude Desktop, Cursor or another agent at /api/mcp and its read tools become available there — the same tools, against the same data. The write tool is deliberately not exposed: the approval gate lives in Relay's interface, so federating the write would hand an external client a way around it.
You can see how it is wired, live. The architecture view is not a diagram — nodes light up along the path a request actually took, with each specialist listing the tools it called and how long they took.

The agents
| Agent | Owns | Tools |
|---|---|---|
| Relay (orchestrator) | Routes the request, synthesises the answer, owns the write path | 2 delegations + 1 write |
| Operations specialist | Orders, shipments, customers, tickets, operational overview | 7 read |
| Knowledge specialist | The document library, through hybrid retrieval | 1 read |
Delegation is not for speed — it costs latency. It buys reliable tool selection (six related tools beat fourteen unrelated ones), clean per-specialist context, and a structurally isolated write path.
The tools
| Tool | Effect | What it does |
|---|---|---|
find_delayed_orders |
read | Orders past their estimated delivery date and not delivered |
search_orders |
read | Orders by status, customer or recency |
get_order |
read | One order in full: items, shipment, tickets, refunds |
track_shipment |
read | Where a shipment is, whether it is late and by how many days |
search_tickets |
read | Support tickets by status, priority or category |
get_customer |
read | One customer with order and ticket history |
get_operations_summary |
read | Counts by status, delays by carrier, 14-day volume trend |
search_knowledge |
read | Hybrid retrieval over uploaded documents |
issue_refund |
write | Issues a refund. Human approval required. Capped and idempotent. |
How retrieval works

Ingestion, once per document: upload → extract → chunk (~1000 chars, 150 overlap) → embed (multilingual MiniLM, 384d) → store in pgvector.
Query, every question: embed → vector search and full-text search in parallel → fuse by reciprocal rank → top 5 passages with their source.
Both searches, because neither is enough alone. Vector similarity finds a passage that means the same thing in different words and misses an exact SKU. Full-text finds the exact token and misses the paraphrase. RRF merges the two rankings without calibrating scores between incomparable systems.
The embedder is multilingual on purpose: an English-only model scores a Spanish question against an English policy at 0.18, barely above the 0.02 it gives unrelated text. Cross-language retrieval would silently return noise. The multilingual model scores the same pair at 0.43.
Running it
Requirements: Node 22+, Docker, and an API key from DeepSeek or Anthropic.
npm install # also generates the Prisma client
cp .env.example .env # set RELAY_PROVIDER and the matching key
npm run db:up # PostgreSQL + pgvector on port 5440
npm run db:push # create the schema
npm run db:seed # demo dataset + policy documents
npm run dev
Open http://localhost:3000.
Bring your own key. The Settings tab in the console accepts an API key that is stored in your browser only, sent as a request header, forwarded to that provider and discarded. It is never written to the database, never logged, and never appears in the audit trail.
| Command | What it does |
|---|---|
npm run db:up / db:down |
Start / stop PostgreSQL |
npm run db:reset |
Wipe and reseed everything |
npm run db:seed:docs |
Reset just the document library |
npm run docs:pdf |
Rebuild the case study PDFs |
The seed is deterministic — the same orders, delays and tickets on every run — and dates are generated relative to now, so the data never looks stale.
Try it
Sample documents to upload live in docs/sample-uploads/, with the questions to ask after each one and the correct answers. One of them deliberately contradicts a seeded policy, which is what happens at a real client.
Project layout
prisma/
schema.prisma Data model — one datastore
seed.ts Deterministic business dataset
seed-documents.ts Policy documents into the knowledge base
src/
app/api/chat/route.ts The agent endpoint
lib/
agents.ts Orchestrator + specialists, delegation tools
tools.ts The 9 tools
rag/ Chunking, ingestion, hybrid search
embeddings.ts Local multilingual embedder
audit.ts Tool call recording
model.ts Provider resolution, bring-your-own-key
components/
console.tsx The one-panel console
architecture.tsx Live architecture canvas
renders/ Generative UI: tables, records, charts
Connecting over MCP
// claude_desktop_config.json
{
"mcpServers": {
"relay": { "url": "http://localhost:3000/api/mcp" }
}
}
Eight read tools become available: orders, shipments, customers, tickets, the operational summary and hybrid document search. issue_refund is absent by design — reads are safe to federate, writes stay behind the human gate.
Deployment
Self-hosted. A standalone Next.js build and a PostgreSQL container behind a reverse proxy. No managed platform required and no vendor lock-in introduced.
Security
.env and every .env.* except .env.example are gitignored. This repository is public — no key, token or connection string belongs in a tracked file.
The demo dataset is entirely generated. Harbor & Pine is fictional; no customer, order, address or refund in it refers to a real person.
Documentation
| Document | For |
|---|---|
| Case study (EN) | The full technical write-up |
| MCP exposure · (ES) | How /api/mcp was built, what it exposes and what it does not |
| Caso de estudio (ES) | Spanish edition |
| Sample uploads | Test documents with expected answers |
Built by
IKOM — Haziel Zul and Jorge Bustos.
Relay is a showcase build. Harbor & Pine is a fictional brand and its data is generated; the architecture, the code and the numbers are real and reproducible in the demo.
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