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GraphJin MCP

GraphJin

GraphJin's MCP server gives an agent safe, schema-aware access to SQL and MongoDB instead of raw database credentials

  • 3,236 ★ on the repository
  • Last commit
  • Apache-2.0
MCP serverOfficial

Broad access

Why this level

  • Lets the agent run queries against a working database, including writes where that is permitted
All reasons and checks

dosco/graphjinAuthor:Spacy

Install

Manual install

/plugin marketplace add dosco/graphjin
/plugin install graphjin-mcp@graphjin

The plugin registers the graphjin MCP server; the graphjin binary must be installed for it to work.

Access and checks

How we review

Broad accessThe tool can change data, run commands or handle secrets.

  • Lets the agent run queries against a working database, including writes where that is permitted

This is third-party code. Review the repository files before installing.

What it does

GraphJin compiles GraphQL queries into SQL or MongoDB queries and exposes the same capability as MCP tools. Before querying anything, the agent calls query_catalog and gets the tables, relationships and examples, so it isn't guessing at the schema blind. Access is bounded by an allow-list of queries and a read-only policy where configured, rather than by handing over full database credentials. A built-in server-side agent is also available: one call to ask_graphjin_agent runs the discovery loop itself and returns a typed, evidence-backed answer.

Who it is for. For developers and data analysts who need to give an agent access to a working database without handing out raw credentials.

Good fit when

  • The agent needs to answer questions from PostgreSQL, MySQL, MongoDB or another supported database
  • You need an upfront catalog of tables and relationships so the agent isn't writing arbitrary SQL blind
  • You need to bound the agent to an allow-list of queries and a read-only mode

Not a fit when

  • You just need a plain direct SQL client without a GraphQL and MCP layer on top
  • Your database isn't on GraphJin's supported list

Example request

Find every customer in the database with an overdue invoice from last quarter

MCP

Transport
stdio
Authentication
not required

Environment variables

GRAPHJIN_CONFIG_PATH
Path to the GraphJin configuration folder, defaults to ./config.

Limitations

The graphjin binary must be on PATH and run with access to the project configuration (GRAPHJIN_CONFIG_PATH). GraphJin is primarily a GraphQL-to-SQL compiler and runtime for building applications, and MCP is one mode built on the same core, so wiring it up needs its own schema configuration.

How to disable. Remove the graphjin-mcp plugin via /plugin in Claude Code, or delete the graphjin entry from your agent's mcpServers configuration.

FAQ

Which databases are supported?

PostgreSQL, MySQL, MongoDB, SQLite, Oracle, MSSQL and several cloud databases; the full list is in the project README.

Does the agent need raw database passwords?

No, GraphJin holds the database connection itself, and the agent works through MCP tools and allow-listed queries.

Discussion

No questions or reviews yet.

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README in short

The README presents GraphJin as a compiler and runtime that gives agents one governed graph over databases, files and code through GraphQL and MCP. A dedicated graphjin-mcp plugin registers the MCP server in Claude Code via the graphjin mcp command. Besides one-off queries, it supports watch subscriptions for standing questions and a gj_artifacts store for saved queries and results. Installation is available via npm, Homebrew, Docker or prebuilt Linux and Windows packages.

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