Vector MCP Server

MCP (Model Context Protocol) server for Vector - the Apex Fusion eUTXO L2. Enables AI agents (Claude, GPT, Gemini, or any MCP client) to interact with Vector natively: query balances, send transactions, deploy and interact with smart contracts, manage on-chain agent identities, and submit protocol improvement proposals.

Built on Ogmios + Koios - no Blockfrost dependency.

Vector mainnet is live. Full guides: Vector AI documentation.

Hosted servers - no install

Hosted instances run on both networks, exposing all 24 tools:

Deployment status: both networks are current. Both hosted instances run today's completed migration: testnet since the 2026-07-31 morning merges (auto-deployed from main), mainnet since a deliberate cutover deploy the same day (see docs/architecture/non-custodial-split.md, section 11, "Rollout", for the full history). Both hosted instances are open access - no bearer token is required to connect. Callers are admitted anonymously with per-IP rate limiting. That is an access-control property, and it is separate from custody: neither instance accepts a mnemonic from any caller, with or without a token. Self-hosted deployments can still gate access with MCP_AUTH_TOKENS - see Configuration.

Transport: both hosted instances serve /mcp, the modern Streamable HTTP endpoint. It is the recommended transport and the endpoint listed in the table above. The legacy SSE pair (/sse + /messages) remains available on both hosted instances for clients that need it, deprecated by the MCP spec (2026-07-28 revision) and retained for compatibility.

Connect from Claude Code in one command. No token needed for the hosted instances.

Modern transport (Streamable HTTP) - recommended:

claude mcp add --transport http vector-mcp https://mcp.vector.mainnet.apexfusion.org/mcp

Legacy SSE transport - still answered by both hosted instances:

claude mcp add --transport sse vector-mcp https://mcp.vector.mainnet.apexfusion.org/sse

Swap in the testnet host for either command to connect to testnet instead. Self-hosting (below) serves both transports too, and gives every caller open access to your own instance unless you set MCP_AUTH_TOKENS.

Security notice: the non-custodial migration is complete, in this codebase and on both hosted instances, as of the 2026-07-31 cutover deploy. No tool in this repository accepts a mnemonic, private key, or any other key material. Every build_* tool constructs an unsigned transaction from a wallet address only, and every signing operation happens locally on your own machine, through the local signer companion. Broadcast the signed result with vector_submit_transaction - your seed phrase never leaves your machine, and no server running this release ever holds one. This is enforced mechanically in the code, not just by convention: the builder's custody boundary test scans every source file for key-material vocabulary against an allowlist that is now empty and pinned at size zero, so a future change cannot silently reintroduce a mnemonic parameter without failing that test by name. This describes this release and the 2026-07-31 deploy specifically - a later deploy is a separate operational action, not automatically covered by this notice; see the deployment status note above and docs/architecture/non-custodial-split.md for the full rollout history.

Self-hosting instructions are below.

Related MCP server: Somnia MCP Server

Local signer (non-custodial path)

packages/signer is a local MCP server that holds your key and signs transactions locally instead of handing your mnemonic to a shared host. It has no network access at all: stdio transport only, no Provider, no egress, so a key given to it never reaches a shared server or your model provider. Four tools: vector_signer_get_address, vector_signer_decode_transaction, vector_signer_sign, vector_signer_get_spend_limits.

In this codebase, this signer is the single signing point for every family the builder exposes. The full non-custodial flow is live in this release for all of them: vector_signer_get_address → build_* → vector_signer_sign → vector_submit_transaction → vector_await_transaction. No step in that chain puts a mnemonic in front of a server running this code, or your model provider, for any tool. The build → submit → await half is E2E-proven on Vector testnet across the wallet/tx, smart-contract, agent-registry, and self-improvement families, including the first keyless-built proposal submission the deployed self-improvement module validator has ever accepted; see packages/signer/README.md for exactly what that testing does and does not exercise on the signer's side. This describes the code, not every deployment of it - see the deployment status note above.

See packages/signer/README.md for configuration, tools, and known limitations.

Features

• Wallet & queries - balances, UTxOs, and transaction history for any address (no key material)

• Keyless transaction building - build unsigned AP3X/token/multi-output transactions and contract interactions; sign locally, broadcast via submit

• Smart contracts - deploy Plutus/Aiken validators, lock and spend UTxOs at script addresses (keyless)

• Agent registry - register, discover, update, transfer, and deregister on-chain AI agent identities via soulbound NFTs (keyless - build, sign locally, broadcast)

• Agent messaging - send on-chain messages between agents via TX metadata (keyless)

• Self-Improvement Module - browse, submit, critique, and endorse improvement proposals; the on-chain module is live on Vector mainnet, and every write tool is keyless in this codebase

• Safety controls - per-identity rate limiting; spend limits for every family are enforced by the local signer, per user - the server holds no spend-limit state of its own

• Dual transport - modern Streamable HTTP (/mcp) plus legacy SSE (/sse + /messages, deprecated by the MCP spec (2026-07-28 revision), retained for compatibility)

MCP Tools (24)

Wallet & Queries

Transactions

Smart Contracts

Agent Registry

Self-Improvement Module

Agent DIDs follow the format: did:vector:agent:{policyId}:{nftAssetName}

Example non-custodial flow for a registry op: vector_build_register_agent → vector_signer_sign → vector_submit_transaction → vector_await_transaction.

Self-hosting

1. Install and build

Requires Node.js >= 22 (matches engines in every package.json and the Dockerfile's node:22-alpine base).

npm install
npm run build

Dependency advisories. npm audit currently reports 1 low-severity advisory: an esbuild arbitrary-file-read issue that only triggers via its own Windows dev server, reachable solely through tsup (a build-time-only dependency, absent from the production image, which installs with npm ci --omit=dev). As of 2026-07-31 this tree carried 44 advisories, including 1 critical (tar, GHSA-23hp-3jrh-7fpw) that arrived because @cardano-sdk/crypto - pulled in transitively through @lucid-evolution/lucid - declared the entire npm CLI package as a runtime dependency. That dependency was dead weight: @cardano-sdk/crypto's own published code never requires npm, and neither npm nor tar appears anywhere in this server's built bundle. Regenerating the lockfile picked up a newer @cardano-sdk/crypto release that dropped the stray dependency outright, clearing all 43 of those advisories without any override needed; package.json also carries a defensive overrides pin on tar and brace-expansion against future regressions, though it is not what resolved this one.

2. Configure environment (optional)

cp .env.example .env
# Edit .env with your endpoint URLs (defaults point to Vector testnet; mainnet URLs below)

Every build_* tool is keyless: it takes a wallet address, never a mnemonic. No tool call against this server ever needs a mnemonic parameter, for any family - see the security notice above.

3. Run

npm start
# Server listens on port 3000 (configurable via PORT env var)

Connect with the modern transport:

claude mcp add --transport http vector-mcp http://localhost:3000/mcp

Add --header "Authorization: Bearer <your-token>" if you set MCP_AUTH_TOKENS. The legacy SSE pair (/sse + /messages, deprecated by the MCP spec, retained for compatibility) is still available at http://localhost:3000/sse for clients that need it.

If this instance will be reachable by anyone but you, set MCP_AUTH_TOKENS first - see Configuration below.

4. Add to Claude Desktop

Add to your Claude Desktop MCP config (claude_desktop_config.json):

{
  "mcpServers": {
    "vector": {
      "command": "node",
      "args": ["/path/to/vector-mcp-server/packages/builder/build/index.js"],
      "env": {
        "VECTOR_OGMIOS_URL": "https://ogmios.vector.testnet.apexfusion.org",
        "VECTOR_SUBMIT_URL": "https://submit.vector.testnet.apexfusion.org/api/submit/tx",
        "VECTOR_KOIOS_URL": "https://koios.vector.testnet.apexfusion.org/",
        "VECTOR_EXPLORER_URL": "https://vector.testnet.apexscan.org"
      }
    }
  }
}

For mainnet, use the mainnet endpoint table below. (No local setup needed if you use the hosted servers above.)

Docker

npm run build
docker build -t vector-mcp .
docker run -p 3000:3000 vector-mcp

If this instance will be reachable by anyone but you, set MCP_AUTH_TOKENS first - see Configuration below (docker-compose.yml in this repo binds 127.0.0.1 by default; the command above does not).

Configuration

The four numeric knobs above fail loudly at startup on a malformed value: anything that is not a plain integer, or is below its listed minimum, raises a startup error naming the variable and the value it got, rather than silently falling back to some other behavior (an unparseable rate limit silently disabling rate limiting, for example).

This server has no spend-limit or audit-log configuration of its own: it holds no key material for any family, so it has nothing left to limit. Every spend limit, and the audit log recording it, lives in your local signer instead - see VECTOR_SIGNER_SPEND_LIMIT_PER_TX / VECTOR_SIGNER_SPEND_LIMIT_DAILY / VECTOR_SIGNER_AUDIT_LOG_PATH in packages/signer/README.md.

Running a public instance? Set MCP_AUTH_TOKENS to gate access to known callers, each with its own rate-limit budget. With MCP_AUTH_TOKENS unset, callers are admitted anonymously with per-client-IP rate limits; the deployment's reverse proxy supplies the client address via the rightmost X-Forwarded-For entry. Tracked identities are capped (LRU); eviction resets a bucket's budget - a memory bound, not a security boundary, since an attacker rotating enough source IPs can still defeat per-IP limiting at a tier only the reverse proxy or network layer can police. /mcp sessions get the same per-identity treatment: idle sessions are reaped (VECTOR_MCP_SESSION_IDLE_MS, swept every VECTOR_MCP_SESSION_SWEEP_MS), and concurrent sessions per identity are capped (VECTOR_MCP_MAX_SESSIONS_PER_IDENTITY) - see the Configuration table above for defaults and minimums.

Malformed values fail loudly. The server refuses to start if MCP_AUTH_TOKENS contains an empty token, a token with embedded whitespace, a duplicate token, or a value where every comma-separated entry is blank (e.g. a stray ,,,). Each case raises a startup error that names the problem but never echoes a token value. Commas delimit entries and cannot be escaped, so generate tokens from a comma-free charset (hex / base64url / alphanumeric).

Error responses do not echo configured endpoints. This covers every failure mode a network call can produce, not just an HTTP-level rejection: a DNS failure, a dropped connection, and a malformed (non-JSON) response body are all sanitised the same way an ordinary 4xx/5xx status is - the underlying HTTP client is the platform's native fetch, chosen in part because its own errors do not embed the request URL the way some polyfills do. A failed Ogmios or Koios query is this server's own infrastructure problem, not something the caller can act on - it is reported by service name and status only, for example "Ogmios request failed (queryLedgerState/utxo): 503 Service Unavailable" or, for a connection failure, "...: network error". A rejected transaction submission is different: the ledger's verdict on the CALLER'S OWN transaction (a bad input, an unmet script condition, a fee too small) stays in the response, since it is the feedback loop an agent needs to self-correct after build → sign → submit - only URL-shaped content is scrubbed out of it first, for example "Transaction submission rejected (400 Bad Request): ValueNotConservedUTxO...". A NETWORK failure to even reach the submit API is reported as an infrastructure failure instead ("...: network error"), never worded as a ledger rejection, since nothing looked at the transaction at all. Neither case ever echoes the configured VECTOR_OGMIOS_URL / VECTOR_KOIOS_URL / VECTOR_SUBMIT_URL value itself, and full unscrubbed detail always goes to the server's own console.error log for operators. Known limit: the submission-rejection scrub removes http(s) URLs and the three endpoints above by name - a rejection body that happens to name some other internal hostname passes through unscrubbed, bounded by a 2000-character cap.

Mainnet endpoints

Testing

npm run test:unit

No wallet, no network - pure logic only (CBOR encode/decode assertions).

npm run test:smoke

Builds the server, boots it, and asserts the exposed tool inventory matches the checked-in snapshot. No wallet, no external network. CI runs this and test:unit on every PR.

echo "your mnemonic words here" > packages/builder/mnemonic.txt
npm run test:integration

Requires mnemonic.txt in packages/builder/ containing a funded Vector testnet mnemonic. Covers the core tools end-to-end against Vector testnet, including the full agent lifecycle: register, discover, profile, update, transfer, message, and deregister (all keyless now: build → sign → submit → await per step). Also runs keyless-build.test.ts, registry-keyless.test.ts, and self-improvement-keyless.test.ts - tier-1 suites needing no mnemonic at all, each building unsigned transactions against live public data only (vector_build_send_tokens is covered offline, by unit tests and the legacy suite above; self-improvement-keyless.test.ts covers critique, endorse, and proposal-lock builds, plus a not-found rejection path on proposal-spend). Set VECTOR_E2E_SUBMIT=1 to additionally run each family's gated end-to-end suite, fully on-chain: keyless-e2e.test.ts lands one real self-send (~0.16 AP3X fee); registry-e2e.test.ts runs a full register → update → deregister agent lifecycle (the 10 AP3X deposit round-tripped exactly, fees only as net cost); self-improvement-e2e.test.ts locks and spends a real improvement proposal through the deployed module validator, then critiques and endorses it (≈48 AP3X in stakes and module minimums, plus six transaction fees, one-way - the stakes are locked by the module's own design, not lost). Set LEGACY_FULL=1 to additionally exercise the same self-improvement lock → spend sequence inside run.test.ts itself (off by default, since self-improvement-e2e.test.ts already proves that exact path). Never runs in CI.

npm run test:smoke:signer

Builds the local signer (packages/signer), boots it over stdio, and exercises all four of its tools, including the fail-closed audit-write-failure path. No wallet, no network. CI runs this on every PR alongside the two smoke tests above.

export VECTOR_SIGNER_MNEMONIC_FILE=/absolute/path/to/testnet-mnemonic.txt
npm run test:integration:signer

Requires a funded Vector testnet wallet. Builds a real unsigned transaction the way the hosted builder does (no key), then has the local signer decode, policy-check, and sign it against live chain data. Never submits. Never runs in CI. See packages/signer/README.md.

Architecture

┌──────────────────────┐             ┌──────────────────────────┐
│  Claude / GPT / etc. │◄───────────►│  vector-mcp-server       │
│  (any MCP client)    │ /sse + /mcp │                          │
└──────────────────────┘             │  ┌────────────────────┐  │
                                     │  │ Rate Limiter        │  │
                                     │  │ (60 calls/min)      │  │
                                     │  └────────┬───────────┘  │
                                     │           │               │
                                     │  ┌────────▼───────────┐  │
                                     │  │ Lucid + Ogmios     │  │
                                     │  │ Provider            │  │
                                     │  └────────┬───────────┘  │
                                     │           │               │
                                     │  ┌────────▼───────────┐  │
                                     │  │ Ogmios / Koios /   │  │
                                     │  │ Submit API          │  │
                                     │  └────────────────────┘  │
                                     └──────────────────────────┘

No safety layer sits between the rate limiter and the provider: this server holds no key material for any family, so it has no spend limits of its own left to enforce. Every spend limit lives in your local signer instead.

About Vector

Vector is Apex Fusion's eUTXO L2, running Cardano mainnet parameters (Conway era, Plutus V3). Sub-1-second optimistic finality and deterministic fees make it a natural chain for AI agent workloads. Mainnet is live.

• Docs: https://apex-fusion.github.io/vector-ai-documentation/

• Explorer (mainnet): https://vector.apexscan.org/en/

• Explorer (testnet): https://vector.testnet.apexscan.org

• Apex Fusion: https://apexfusion.org