# DataContractGate (npm · @nightmoose/contractgate-mcp-server)

Infer, dry-run, deploy, and inspect DataContractGate semantic data contracts.

- Trust score: 91/100 (high trust)
- Change this week: +18
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-10-17

## Components

- npm · `@nightmoose/contractgate-mcp-server`: 91/100 (this document), [markdown](https://verifymcp.io/servers/nightmoose-contractgate/nightmoose-contractgate-mcp-server.md), [page](https://verifymcp.io/servers/nightmoose-contractgate/nightmoose-contractgate-mcp-server)

## Channel facts

- Registry: `npm`
- Package: `@nightmoose/contractgate-mcp-server`
- Version: `0.4.0`
- Transport: `stdio`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-10-17.

- **Supply Chain Security**: 100/100
  - No malware found by supply-chain analysis.
  - No known CVEs affecting this package version or its production dependencies.
  - No install/post-install scripts declared.
  - 0 of 3 dependencies flagged as unhealthy.
- **Provenance & Transparency**: 100/100
  - Source repository is publicly reachable at the declared URL.
  - Cryptographically verified build provenance (signed, bound to nightmoose/contractgate).
  - Clear OSI-approved license (MIT).
  - Actively maintained (last published 3 days ago).
  - Publishes a security disclosure policy (SECURITY.md).
- **Schema Quality & AI Usability**: 85/100
  - 100% of prompts and resources have a non-trivial description (not blank, and not just the item's name).
  - AI-judged instruction clarity (good).
  - Tool/resource definitions use about 618 tokens (~103/item across 6 items; 6 tools + 0 resources), lean.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 57/100
  - Stability observed for 17 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 98/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 95% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - All 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation.
  - An AI judge read all 6 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a current MCP spec version (2026-07-28).

## Install

### How do I install the DataContractGate MCP server?

DataContractGate runs locally as an npm package, launched with npx -y @nightmoose/contractgate-mcp-server. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add nightmoose-contractgate -- npx -y @nightmoose/contractgate-mcp-server
```

### Cursor

```json
{
  "mcpServers": {
    "nightmoose-contractgate": {
      "command": "npx",
      "args": [
        "-y",
        "@nightmoose/contractgate-mcp-server"
      ]
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "nightmoose-contractgate": {
      "command": "npx",
      "args": [
        "-y",
        "@nightmoose/contractgate-mcp-server"
      ]
    }
  }
}
```

### Codex

```bash
codex mcp add nightmoose-contractgate -- npx -y @nightmoose/contractgate-mcp-server
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "nightmoose-contractgate": {
      "type": "local",
      "command": [
        "npx",
        "-y",
        "@nightmoose/contractgate-mcp-server"
      ],
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add nightmoose-contractgate --command npx --arg -y --arg @nightmoose/contractgate-mcp-server
```

### Hermes

```yaml
mcp_servers:
  nightmoose-contractgate:
    command: "npx"
    args: ["-y", "@nightmoose/contractgate-mcp-server"]
```

### Netclaw

```json
{
  "McpServers": {
    "nightmoose-contractgate": {
      "Transport": "stdio",
      "Command": "npx",
      "Arguments": [
        "-y",
        "@nightmoose/contractgate-mcp-server"
      ]
    }
  }
}
```

### Vellum

```bash
assistant mcp add nightmoose-contractgate -t stdio -c npx -a -y @nightmoose/contractgate-mcp-server
```

### Other

```json
{
  "mcpServers": {
    "nightmoose-contractgate": {
      "command": "npx",
      "args": [
        "-y",
        "@nightmoose/contractgate-mcp-server"
      ]
    }
  }
}
```

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-10-16 (score 91, +1)

No change was recorded against any check on this day. Stability & Change Management went from 50 to 53. That category is still filling its 30-day observation window: 15 days of observed history at the previous scan, 16 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-14 (score 90, +51)

- [security improvement] Injection markers: unverified → pass
- [security improvement] Known CVEs: unverified → pass
- [functional improvement] Stability: unverified → 0.47
- [functional improvement] Schema quality: unverified → 100
- [functional improvement] Tool coverage: unverified → 100
- [functional improvement] MCP protocol: unverified → pass
- [functional improvement] Dependency health: unverified → 1.00
- [functional] Package version: 0.3.0 → 0.4.0

### 2026-10-13 (score 39, −50)

- [security regression] Known CVEs: pass → unverified
- [security regression] Stability: 0.40 → unverified
- [security regression] Tool safety: pass → unverified
- [functional regression] Dependency health: 1.00 → unverified
- [functional regression] Capabilities: pass → unverified
- [functional regression] Tool coverage: 100 → unverified
- [functional regression] Schema quality: 100 → unverified
- [functional] Package version: 0.3.0 → 0.4.0
- [functional] Package version: 0.3.0 → 0.3.2
- [functional] Package version: 0.3.0 → 0.3.1

### 2026-10-12 (score 89, +16)

- [security improvement] Provenance: fail → pass
- [security] The attested source repository moved: nightmoose/contractgate
- [functional improvement] Stability: unverified → 0.40
- [functional] Package version: 0.2.0 → 0.3.0

### 2026-10-01 (score 73, +15)

- [security improvement] Malware scan: unverified → pass

### 2026-09-30 (score 58)

First indexed and scored.

## MCP tools (6)

### `infer_contract` (~91 tokens)

Infer a contract from sample events

Generate draft DataContractGate YAML from real JSON sample events via POST /contracts/infer. Does not persist. Review and write the YAML to contracts/<name>.yaml before deploying.

Input parameters:

- `description` (string): Optional contract description
- `name` (string, required): Contract name, snake_case, e.g. user_events
- `samples` (array, required): 1–20 real event objects. Do not invent them.

### `validate_events` (~152 tokens)

Validate events against a contract

Validate events. Pass contract_id to hit POST /v1/ingest/{id} (dry_run defaults true — no audit, quarantine, or usage). Pass yaml_content to hit POST /playground/validate per event (never persists). Exactly one of contract_id or yaml_content. 207/422 responses are returned as data so you can apply each violation's suggestion.

Input parameters:

- `contract_id` (string): Deployed contract UUID from deploy_contract
- `dry_run` (boolean): Ingest only. Default true. Set false only after a successful dry run.
- `events` (array, required): Event objects to validate
- `yaml_content` (string): In-flight contract YAML; uses the playground, never persists

### `deploy_contract` (~118 tokens)

Deploy a contract to stable

POST /contracts/deploy — find-or-create by name, insert YAML as stable, deprecate prior stable. 409 if that (name, version) exists: bump version in the YAML. Refused while quarantine is pending. Save the returned contract_id.

Input parameters:

- `deployed_by` (string): Actor recorded on the version row
- `name` (string, required): Contract name matching the YAML name: field
- `source` (string): Logical feed name, e.g. app-backend
- `yaml_content` (string, required): Full contract YAML

### `get_quarantine` (~63 tokens)

List quarantined events

GET /quarantine — rejected events for the caller's org, newest first, with violation details.

Input parameters:

- `contract_id` (string): Restrict to one contract
- `limit` (integer): Default 100, max 500
- `offset` (integer)

### `list_contracts` (~20 tokens)

List contracts

GET /contracts — identities the API key can see.

### `egress_validate` (~174 tokens)

Validate an outbound payload

POST /egress/{contract_id}. Validates an outbound payload against a deployed contract. dry_run defaults true — no audit row or quarantine. Returns the full response body (200/207/422) so you can read violations and repair the payload. Forward response.payload only — never the original body after a block or fail.

Input parameters:

- `contract_id` (string, required): Deployed contract UUID
- `disposition` (string): Default block. block = drop failing records from payload; fail = reject entire batch; tag = pass through with flags.
- `dry_run` (boolean): Default true. Set false only after a successful dry run — live calls write audit and quarantine rows.
- `events` (array, required): Outbound payload objects to validate
- `version` (string): Pin a specific contract version. Default: latest stable.

## Diagnostics

Captured diagnostic sections: Provenance, Dependencies. The full working is on the page: https://verifymcp.io/servers/nightmoose-contractgate/nightmoose-contractgate-mcp-server#diagnostics

## Score history

- 2026-10-17: 91
- 2026-10-16: 91
- 2026-10-15: 90
- 2026-10-14: 90
- 2026-10-13: 39
- 2026-10-12: 89
- 2026-10-11: 73
- 2026-10-07: 73
- 2026-10-04: 73
- 2026-10-03: 73
- 2026-10-02: 73
- 2026-10-01: 73
- 2026-09-30: 58

## Common questions

### What is the DataContractGate MCP server?

DataContractGate is an MCP server listed in the public MCP registry as io.github.nightmoose/contractgate. Infer, dry-run, deploy, and inspect DataContractGate semantic data contracts. This page covers its npm package (@nightmoose/contractgate-mcp-server).

### Is the DataContractGate MCP server safe to use?

DataContractGate scores 91 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 17 October 2026. It declares no install or post-install scripts. Its build provenance is signed and verified. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the DataContractGate MCP server expose?

DataContractGate exposes 6 tools: infer_contract, validate_events, deploy_contract, get_quarantine, list_contracts, egress_validate. Their descriptions and schemas cost roughly 618 tokens of context every time the server is loaded.

### Is the DataContractGate MCP server still maintained?

DataContractGate is still listed as active in the MCP registry. We last reached this channel on 17 October 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

### What licence is the DataContractGate MCP server under?

DataContractGate declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.

## Links

- npm package: https://www.npmjs.com/package/@nightmoose/contractgate-mcp-server
- Socket report: https://socket.dev/npm/package/@nightmoose/contractgate-mcp-server
- Repository: https://github.com/nightmoose/contractgate
- Website: https://app.datacontractgate.com/mcp-reference.md
- Changelog RSS feed: https://verifymcp.io/servers/nightmoose-contractgate/nightmoose-contractgate-mcp-server.xml
- Changelog JSON feed: https://verifymcp.io/servers/nightmoose-contractgate/nightmoose-contractgate-mcp-server.json
- HTML version of this page: https://verifymcp.io/servers/nightmoose-contractgate/nightmoose-contractgate-mcp-server