Dataset Join & Merge
https://dataset-join-merge.nerolabs.workers.dev/mcp ↗
Description
Join two lists of JSON rows on a key, like SQL or VLOOKUP: left, inner, full, anti joins, union.
What our measurements say
Dataset Join & Merge is a remote MCP server published at dataset-join-merge.nerolabs.workers.dev. It has been probed 5 times since 9/13/2026. It answered in 5 of them (100.0%), a near-uninterrupted record. Median response time is 149 ms, placing it among the faster endpoints. It offers a narrow, focused set of 2 tools. On the protocol side it still runs 2025-11-25 and has not moved to the newer spec.
Agent readability score
Can an LLM agent pick the right tool here — names, descriptions and parameter clarity are assessed.
Agent readability score
Agent readability score
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| Run | Era | Modern | ms | Legacy | ms | Versions |
|---|---|---|---|---|---|---|
| 2026-09-13 12:47:19 | Legacy | 200 | 149 | 200 | 149 | 2025-06-18 |
| 2026-09-13 10:45:14 | Legacy | 200 | 136 | 200 | 159 | 2025-06-18 |
| 2026-09-13 08:43:04 | Legacy | 200 | 137 | 200 | 147 | 2025-06-18 |
| 2026-09-13 06:40:42 | Legacy | 200 | 178 | 200 | 181 | 2025-06-18 |
| 2026-09-13 04:35:29 | Legacy | 200 | 126 | 200 | 140 | 2025-06-18 |
Schema compliance
tools/list structure, inputSchema validity, and a functional smoke test — the components of the 0-100 score.
- tools/list schema valid
- inputSchema is valid JSON Schema
- Smoke test passed · last run:
- Cold-start: cold 42ms → warm 44ms (penalty 0ms)
Tools
Tools the server advertised in the latest measurement — measured, not catalog-claimed.
list_capabilitiesReturns 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_rowsJoins 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
leftRowsarrayrequiredrightRowsarrayrequiredleftKeyFieldsarrayrightKeyFieldsarrayjoinTypestringkeyMatchingstringrightFieldsarrayonFieldConflictstringrightFieldPrefixstringmultipleMatchesstringincludeJoinInfoboolean
Availability history
Each block is one measurement round. Green: working response. Amber: responded but the server was returning errors (5xx). Red: no response at all.
Era history
Each cell is one probe run. Faded cells are incomplete probes — one leg did not answer, so the era is inconclusive.
Response time history
The two probe legs separately: modern server/discover and legacy initialize.
Event log
Derived by comparing consecutive probes — changes in era, protocol version, build and reachability.
- Added to watch — era: Legacy
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[](https://mcpmetrics.io/servers/io-github-nero-engine-dataset-join-merge)<a href="https://mcpmetrics.io/servers/io-github-nero-engine-dataset-join-merge"><img src="https://mcpmetrics.io/badge/io.github.Nero-Engine/dataset-join-merge/era.svg" alt="mcpmetrics"></a>You are seeing the last 7 days. Sign up for the full history. Which check failed and why is in the dashboard.
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