# Dataset Join & Merge (remote · dataset-join-merge.nerolabs.workers.dev)

Join two lists of JSON rows on a key, like SQL or VLOOKUP: left, inner, full, anti joins, union.

- Trust score: 59/100 (low)
- Change this week: +3
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-20

## Components

- remote · `dataset-join-merge.nerolabs.workers.dev`: 59/100 (this document), [markdown](https://verifymcp.io/servers/nero-engine-dataset-join-merge/dataset-join-merge.md), [page](https://verifymcp.io/servers/nero-engine-dataset-join-merge/dataset-join-merge)

## Channel facts

- Endpoint: `https://dataset-join-merge.nerolabs.workers.dev/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `0.1.0`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, 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 2026-09-20.

- **Endpoint Security**: 46/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - Authorisation not fully verified: no authorisation is required to call this server, and 2 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe.
  - HTTPS enforcement could not be verified: the plaintext port answered with HTTP 405, which proves neither a plaintext path nor enforcement.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 60/100
  - AI-judged instruction clarity (excellent).
  - Context-footprint check failed: tool/resource definitions use about 793 tokens (~396/item across 2 items; 2 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 23/100
  - Stability observed for 7 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% 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.
  - We read all 2 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 3 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 60/100
  - Spec-recency check failed: implements MCP spec 2025-06-18; the latest is 2026-07-28.

## Install

### How do I install the Dataset Join & Merge MCP server?

Dataset Join & Merge is a hosted endpoint at https://dataset-join-merge.nerolabs.workers.dev/mcp, so there is nothing to install locally. 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 --transport http nero-engine-dataset-join-merge 'https://dataset-join-merge.nerolabs.workers.dev/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "nero-engine-dataset-join-merge": {
      "url": "https://dataset-join-merge.nerolabs.workers.dev/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "nero-engine-dataset-join-merge": {
      "type": "http",
      "url": "https://dataset-join-merge.nerolabs.workers.dev/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.nero-engine-dataset-join-merge]
url = "https://dataset-join-merge.nerolabs.workers.dev/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "nero-engine-dataset-join-merge": {
      "type": "remote",
      "url": "https://dataset-join-merge.nerolabs.workers.dev/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add nero-engine-dataset-join-merge --url 'https://dataset-join-merge.nerolabs.workers.dev/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  nero-engine-dataset-join-merge:
    url: "https://dataset-join-merge.nerolabs.workers.dev/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "nero-engine-dataset-join-merge": {
      "Transport": "http",
      "Url": "https://dataset-join-merge.nerolabs.workers.dev/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add nero-engine-dataset-join-merge -t streamable-http -u 'https://dataset-join-merge.nerolabs.workers.dev/mcp'
```

### Other

```json
{
  "mcpServers": {
    "nero-engine-dataset-join-merge": {
      "type": "http",
      "url": "https://dataset-join-merge.nerolabs.workers.dev/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## 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.

### 2026-09-20 (score 59, +1)

No change was recorded against any check on this day. Stability & Change Management went from 20 to 23. That category is still filling its 30-day observation window: 6 days of observed history at the previous scan, 7 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-18 (score 58, +1)

No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-15 (score 57, +1)

No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-14 (score 56, 0)

- [functional improvement] Stability: unverified → 0.03

### 2026-09-13 (score 56)

First indexed and scored.

## MCP tools (2)

### `list_capabilities` (~52 tokens)

Returns every join type, key matching mode, conflict strategy and fan-out mode this server supports, the fields it adds to each row, and the input and output row limits per call. Free, processes no data.

### `join_rows` (~687 tokens)

Joins two lists of JSON rows on a shared key, like a SQL join or a spreadsheet VLOOKUP, and returns the combined rows plus a summary: how many rows matched on each side, match rates, and warnings for duplicate keys, rows missing the key and key fields that exist on no row. Use it to enrich a list with fields from a lookup table (left join), keep only the overlap (inner), combine two sources into one table (full), find rows in one list that are missing from the other (leftAnti or rightAnti), or stack two same-shape lists (union). Keys match case-insensitively with whitespace trimmed by default, and the key can have a different name on each side (email on the left, contact_email on the right). Input and output rows are capped per call; a many-to-many join that would exceed the output cap is refused with the predicted row count, never truncated. Call list_capabilities for the exact limits.

Input parameters:

- `includeJoinInfo` (boolean): On by default: every row gets _joinStatus ("matched", "left_only", "right_only") and _matchCount. Set false for rows with only your own fields.
- `joinType` (string): Which rows to keep. left (default): every left row, enriched where a match exists. inner: matched rows only. right: every right row. full: everything from both sides. leftAnti: left rows with no matc…
- `keyMatching` (string): normalized (default): case-insensitive, trimmed, repeated spaces collapsed, 123 matches "123". exact: values must be identical.
- `leftKeyFields` (array): The field name(s) on the left rows to match on, for example ["email"], or ["firstName","lastName"] for a composite key. Required for every joinType except union.
- `leftRows` (array, required): The LEFT table: the main rows you want to keep or enrich. Each row is a JSON object; keys may differ between rows.
- `multipleMatches` (string): When one key matches several right rows. all (default): one output row per matching pair, like SQL. first: only the first matching right row, like VLOOKUP, so each left row appears once.
- `onFieldConflict` (string): When a right field has the same name as a left field. prefixRight (default): keep both, the right one renamed with rightFieldPrefix. keepLeft: ignore the right value. keepRight: overwrite the left va…
- `rightFieldPrefix` (string): Prefix for conflicting right fields when onFieldConflict is prefixRight. Default "right_", so price becomes right_price.
- `rightFields` (array): Only copy these fields from the matching right row, like choosing VLOOKUP return columns. Leave out to copy every right field.
- `rightKeyFields` (array): The matching field name(s) on the right rows, in the same order as leftKeyFields, for example ["contact_email"]. Leave out when the right rows use the same names as the left.
- `rightRows` (array, required): The RIGHT table: the lookup rows to pull matching fields from. Each row is a JSON object.

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/nero-engine-dataset-join-merge/dataset-join-merge#diagnostics

## Score history

- 2026-09-20: 59
- 2026-09-19: 58
- 2026-09-18: 58
- 2026-09-17: 57
- 2026-09-16: 57
- 2026-09-15: 57
- 2026-09-14: 56
- 2026-09-13: 56

## Common questions

### What is the Dataset Join & Merge MCP server?

Dataset Join & Merge is an MCP server listed in the public MCP registry as io.github.Nero-Engine/dataset-join-merge. Join two lists of JSON rows on a key, like SQL or VLOOKUP: left, inner, full, anti joins, union. This page covers its hosted endpoint (https://dataset-join-merge.nerolabs.workers.dev/mcp).

### Is the Dataset Join & Merge MCP server safe to use?

Dataset Join & Merge scores 59 out of 100 on VerifyMCP. 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 Dataset Join & Merge MCP server expose?

Dataset Join & Merge exposes 2 tools: list_capabilities, join_rows. Their descriptions and schemas cost roughly 739 tokens of context every time the server is loaded.

### Does the Dataset Join & Merge MCP server require authentication?

No. We connected to Dataset Join & Merge without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the Dataset Join & Merge MCP server still maintained?

Dataset Join & Merge is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- Remote endpoint: https://dataset-join-merge.nerolabs.workers.dev/mcp
- Repository: https://github.com/Nero-Engine/dataset-join-merge-mcp
- Changelog RSS feed: https://verifymcp.io/servers/nero-engine-dataset-join-merge/dataset-join-merge.xml
- Changelog JSON feed: https://verifymcp.io/servers/nero-engine-dataset-join-merge/dataset-join-merge.json
- HTML version of this page: https://verifymcp.io/servers/nero-engine-dataset-join-merge/dataset-join-merge