Kwdb Mcp Server

What is Kwdb Mcp Server about?

The server exposes KWDB database functionality through MCP tools and resources, allowing LLM agents or clients to execute SQL statements, retrieve schema information, and access pre‑defined documentation prompts.

How to use Kwdb Mcp Server?

1. Build the binary – install Go 1.23+, run make deps then make build to produce bin/kwdb-mcp-server.
2. Run in StdIO (default):

   ./bin/kwdb-mcp-server "postgresql://user:pass@host:port/dbname?sslmode=disable"
   

3. Run in HTTP mode (recommended):

   CONNECTION_STRING="postgresql://user:pass@host:port/dbname?sslmode=disable" PORT=8080 make run-http
   

   The endpoint is http://<host>:<port>/mcp.
4. Run in SSE mode (deprecated) with make run-sse.
5. Use MCP clients to call tools like read-query and write-query, or fetch resources such as kwdb://table/<name>.

Key features of Kwdb Mcp Server

• Read/Write Tools – read-query for SELECT/SHOW/EXPLAIN, write-query for INSERT/UPDATE/DELETE/DDL.
• Automatic LIMIT – adds LIMIT 20 to SELECT statements lacking a limit.
• Standardised JSON responses – consistent success, tool‑error, and resource‑error formats.
• MCP Resources – expose product info, database metadata, and table schemas via URI patterns.
• Embedded MCP Prompts – documentation guides (syntax, installation, performance, etc.) are compiled into the binary.
• Multiple transport modes – StdIO, HTTP (recommended), and SSE (deprecated).
• Security separation – distinct read/write tools and validation of query intent.

Use cases of Kwdb Mcp Server

• LLM‑driven data retrieval – agents query database tables through read-query and receive bounded result sets.
• Automated schema discovery – retrieve table schemas via kwdb://table/<name> for dynamic code generation.
• Self‑service documentation – LLM prompts fetch syntax guides or troubleshooting steps directly from the server.
• Application back‑ends – HTTP mode allows micro‑services to invoke MCP tools over REST without embedding database drivers.
• CLI utilities – StdIO mode enables piping MCP requests from scripts or other command‑line tools.

FAQ from the Kwdb Mcp Server

Q: What happens if I run a SELECT without a LIMIT? A: The server automatically appends LIMIT 20 to protect against large result sets.

Q: Can I change the default LIMIT value? A: Not via configuration; modify the source code in the query‑preparation component and rebuild.

Q: Is SSE still supported? A: Yes, but it is deprecated and will be removed in future releases. Use HTTP mode instead.

Q: How are errors reported? A: Tool errors are wrapped with an isError flag; resource errors follow standard JSON‑RPC error objects.

Q: Do I need to embed the prompts manually? A: No, all Markdown prompt files under pkg/prompts/docs/ are embedded at compile time via Go's embed package.

KWDB MCP Server

中文版

Overview

The KWDB MCP Server is a server implementation based on the MCP (Model Context Protocol) protocol, which provides a set of tools and resources for interacting with the KWDB database and providing business intelligence functionality through the MCP protocol. The KWDB MCP Server supports reading, writing, querying, modifying data, and performing DDL operations.

Architecture

The core process of the KWDB MCP Server consists of the following components:

• Parse MCP protocol: deal with MCP StdIO or HTTP SSE requests.
• Schedule MCP Tools: distribute API requests based on the types of MCP Tools.
• Prepare queries: automatically add the LIMIT 20 clause for SQL queries without a LIMIT clause.
• Format query results: adopt a consistent JSON format for all API responses.

Features

• Read Operations: execute SELECT, SHOW, EXPLAIN, and other read-only queries.
• Write Operations: execute INSERT, UPDATE, DELETE, and CREATE, DROP, ALTER DDL operations.
• Database Information: get information about the database, including tables and their schemas.
• Syntax Guide: access a comprehensive syntax guide for KWDB through Prompts.
• Standard API Response: provide consistent error handling mechanisms.
  • Tools Error: error information is wrapped in result objects with isError flag.

  {
    "content": [{"type": "text", "text": "Query error: error details"}],
    "isError": true
  }
  

  • Resources Error: return standard JSON-RPC error responses directly.

  {
    "jsonrpc": "2.0",
    "id": 1,
    "error": {
      "code": -32002,  // RESOURCE_NOT_FOUND: resource does not exist
      "message": "handler not found for resource URI 'kwdb://table/nonexistent': resource not found"
    }
  }
  

  Or internal processing errors:

  {
    "jsonrpc": "2.0",
    "id": 1,
    "error": {
      "code": -32603,  // INTERNAL_ERROR: internal resource processing error
      "message": "failed to get table schema for 'tablename': database connection error"
    }
  }
  

  • Success Response: tools return result objects, resources return content arrays.
• Automatic LIMIT: prevent large result sets by automatically adding the LIMIT 20 clause to SELECT queries without a LIMIT clause.

Security

The KWDB MCP Server provides the following security measures:

• Provide separate tools for read and write operations.
• Valid queries to ensure that they match the expected operation type.
• Print clear error messages for unauthorized operations.

MCP Resources

MCP Resources allow the KWDB MCP Server to expose data and content that can be read by MCP clients and used as context for LLM interactions. The KWDB MCP Server provides the following MCP Resources:

Resources	URI Format	Description	Example
Product information	kwdb://product_info	Product information, including the version and supported features	kwdb://product_info/
Database metadata	kwdb://db_info/{database_name}	Information about a specific database, including the engine type, comments, and tables	kwdb://db_info/db_shig
Table schema	kwdb://table/{table_name}	Schema of a specific table, including columns and example queries	kwdb://table/user_profile

MCP Tools

The MCP Tools enable the KWDB MCP Server to expose executable functionality to MCP clients. Through MCP Tools, LLMs can interact with external systems. The KWDB MCP Server provides the following MCP Tools.

read-query

The KWDB MCP Server executes the SELECT, SHOW, EXPLAIN statements, and other read-only queries to read data from the database. The read_query function returns the query results in a format of array for your SQL statement. In addition, the KWDB MCP Server will automatically add the LIMIT 20 clause to SELECT queries without a LIMIT clause to prevent large result sets.

Examples:

-- Query table data.
SELECT * FROM users LIMIT 10;

-- List all created tables.
SHOW TABLES;

-- Execute a SQL query and generate details about the SQL query.
EXPLAIN ANALYZE SELECT * FROM orders WHERE user_id = 1;

write-query

The KWDB MCP Server executes data modification queries, including DML and DDL operations.

Examples:

-- Insert data into the table.
INSERT INTO users (name, email) VALUES ('John Doe', 'john@example.com');

-- Update data in the table.
UPDATE users SET email = 'new-email@example.com' WHERE id = 1;

-- Remove data from the table.
DELETE FROM users WHERE id = 1;

-- Create a table.
CREATE TABLE products (id SERIAL PRIMARY KEY, name TEXT, price DECIMAL);

-- Add a column to a table.
ALTER TABLE products ADD COLUMN description TEXT;

-- Remove a table.
DROP TABLE products;

MCP Prompts

MCP Prompts enable the KWDB MCP Server to define reusable prompt templates and workflows that MCP clients can easily surface to users and LLMs. They provide a powerful way to standardize and share common LLM interactions. The KWDB MCP Server provides the following MCP Prompts:

Type	Prompt Name	Description
Database description	db_description	A comprehensive description of KWDB database, including core functions, supported features, and use cases.
Syntax guide	syntax_guide	A comprehensive syntax guide for KWDB, including examples of common queries and best practices.
Cluster management	cluster_management	A comprehensive guide for managing KWDB clusters, including node management, load balancing, and monitoring.
Data migration	data_migration	A guide for migrating data to and from KWDB, including import/export methods and best practices.
Installation	installation	A step-by-step guide for installing and deploying KWDB in various environments.
Performance tunning	performance_tuning	A guide for optimizing KWDB performance, including query optimization, indexing strategies, and system-level tuning.
Troubleshooting	troubleshooting	A guide for diagnosing and resolving common KWDB issues and errors.
Backup and restore	backup_restore	A comprehensive guide for backing up and restoring KWDB databases, including strategies, tools, and best practices.
DBA templates	dba_template	Templates and guidelines for MCP Prompts writing.

Add MCP Prompts

The MCP Prompts are Markdown files stored in the pkg/prompts/docs/ directory. These files are embedded into the binary when compiling the KWDB MCP Server using Go's embed package. Currently, the KWDB MCP Server provides the following Prompts files:

• pkg/prompts/docs/ReadExamples.md: contain read query examples (using the SELECT statement).
• pkg/prompts/docs/WriteExamples.md: contain write query examples (using the INSERT, UPDATE, DELETE, CREATE, ALTER statements).
• pkg/prompts/docs/DBDescription.md: contain the database description.
• pkg/prompts/docs/SyntaxGuide.md: contain the SQL syntax guide.
• pkg/prompts/docs/ClusterManagementGuide.md: contain the cluster management guide.
• pkg/prompts/docs/DataMigrationGuide.md: contain the data migration guide.
• pkg/prompts/docs/InstallationGuide.md: contain the installation guide.
• pkg/prompts/docs/PerformanceTuningGuide.md: contain the performance tuning guide.
• pkg/prompts/docs/TroubleShootingGuide.md: contain the troubleshooting guide.
• pkg/prompts/docs/BackupRestoreGuide.md: contain the backup and restore guide.
• pkg/prompts/docs/DBATemplate.md: contain the database administration template.

To add MCP Prompts, follow these steps:

1. Create a Markdown file in the pkg/prompts/docs/ directory, such as new_usecase.md.
2. Add the variable and load codes in the pkg/prompts/prompts.go file.
3. Create a registration function for the new MCP Prompts.
4. Add the registration function call to registerUseCasePrompts() in the pkg/prompts/prompts.go file.
5. Update the README file.

For details about how to add MCP Prompts, see comments in the pkg/prompts/prompts.go file.

Modify MCP Prompts

To modify MCP Prompts, follow these steps:

1. Edit the specific Markdown file(s) in the pkg/prompts/docs/ directory.
2. Run the make build command to rebuild the application. The updated MCP Prompts will be embedded in the binary.

Build From Source Code

Prerequisites

• Install Go 1.23 or higher.
• Download and install PostgreSQL Driver lib/pq.
• Install and start KWDB, configure the authentication method, and create a database. For details, see the KWDB Documentation Website.
• Create a user with appropriate privileges on tables and databases. For details, see Create Users.

Steps

1. Clone the repository.

   git clone https://gitee.com/kwdb/kwdb-mcp-server
   cd kwdb-mcp-server
   

2. Install dependencies.

   make deps
   

3. Build the application.

   make build
   

If you succeed, the application adopts the following structure.

kwdb-mcp-server/
├── bin/
│   └── kwdb-mcp-server      # Binary executable file
├── cmd/
│   └── kwdb-mcp-server/
│       └── main.go           # The main application
├── pkg/
│   ├── db/
│   │   └── db.go             # Database operations
│   ├── prompts/
│   │   ├── prompts.go        # MCP Prompts
│   │   └── docs/             # MCP Prompts files
│   │       ├── ReadExamples.md     # Read query examples
│   │       ├── WriteExamples.md    # Write query examples
│   │       ├── DBDescription.md    # Database descriptions
│   │       ├── SyntaxGuide.md      # SQL Syntax guide
│   │       ├── ClusterManagementGuide.md # Cluster management guide
│   │       ├── DataMigrationGuide.md    # Data migration guide
│   │       ├── InstallationGuide.md      # Installation guide
│   │       ├── PerformanceTuningGuide.md # Performance tunning
│   │       ├── TroubleShootingGuide.md   # Troubleshooting guide
│   │       ├── BackupRestoreGuide.md     # Backup and restore guide
│   │       └── DBATemplate.md            # DBA templates
│   ├── resources/
│   │   └── resources.go      # MCP Resources
│   ├── server/
│   │   └── server.go         # KWDB MCP Server configurations
│   ├── tools/
│   │   └── tools.go          # MCP Tools
│   └── version/
│       └── version.go        # Version information
├── Makefile                  # Commands for building and running the KWDB MCP Server
└── README.md                 # README file

Start KWDB MCP Server

The KWDB MCP Server supports three transport modes:

• StdIO (Standard Input/Output) mode: Uses standard input/output for communication. This is the default mode.
• HTTP mode (Recommended): Uses HTTP for communication. This is the recommended mode for production.
• SSE (Server-Sent Events) mode (Deprecated): Uses HTTP POST and SSE for communication. This mode will be deprecated soon.

---

StdIO Mode

• Run the KWDB MCP Server with a PostgreSQL connection string:

  ./bin/kwdb-mcp-server "postgresql://<username>:<password>@<hostname>:<port>/<database_name>?sslmode=disable"
  

• Run the KWDB MCP Server using the Makefile:

  CONNECTION_STRING="postgresql://<username>:<password>@<hostname>:<port>/<database_name>?sslmode=disable" make run
  

Parameters:

• username: Username for connecting to the KWDB database.
• password: Password for authentication.
• hostname: IP address of the KWDB database.
• port: Port for connecting to the KWDB database.
• database_name: Name of the KWDB database to access.
• sslmode: SSL mode. Supported values: disable, allow, prefer, require, verify-ca, verify-full. For details, see SSL Mode Parameters.

---

HTTP Mode (Recommended)

• Run the KWDB MCP Server in HTTP mode:

  CONNECTION_STRING="postgresql://<username>:<password>@<hostname>:<port>/<database_name>?sslmode=disable" PORT=8080 make run-http
  

• The HTTP service listens on 0.0.0.0:<port> by default, and the MCP endpoint is http://<host>:<port>/mcp.

Parameters:

• -t or --transport: Transport type, supports stdio, sse, http.
  • stdio: Standard input/output mode
  • sse: SSE mode (deprecated)
  • http: HTTP mode (recommended)
• -p or --port: Listening port for KWDB MCP Server, default is 8080.
• username: Username for connecting to the KWDB database.
• password: Password for authentication.
• hostname: IP address of the KWDB database.
• port: Port for connecting to the KWDB database.
• database_name: Name of the KWDB database to access.
• sslmode: SSL mode. Supported values: disable, allow, prefer, require, verify-ca, verify-full. For details, see SSL Mode Parameters.

---

SSE Mode (Deprecated)

Note

SSE mode is deprecated and will be removed in future releases. Please use HTTP mode if possible.

• Run the KWDB MCP Server in SSE mode:

  CONNECTION_STRING="postgresql://<username>:<password>@<hostname>:<port>/<database_name>?sslmode=disable" PORT=8080 make run-sse
  

Parameters:

• -t or --transport: Transport type, supports stdio, sse, http.
  • stdio: Standard input/output mode
  • sse: SSE mode (deprecated)
  • http: HTTP mode (recommended)
• -p or --port: Listening port for KWDB MCP Server, default is 8080.
• username: Username for connecting to the KWDB database.
• password: Password for authentication.
• hostname: IP address of the KWDB database.
• port: Port for connecting to the KWDB database.
• database_name: Name of the KWDB database to access.
• sslmode: SSL mode. Supported values: disable, allow, prefer, require, verify-ca, verify-full. For details, see SSL Mode Parameters.

Integrate with LLM Agents

For details about how the KWDB MCP Server integerates with LLM Agents, see Integrate with LLM Agents.

Troubleshooting

For details about how to troubleshoot the KWDB MCP Server, see Troubleshooting.

Documentation

For documentation about the KWDB MCP Server, see the KWDB Documentation Website.

Future Enhancements

• Query history: implement query history functionality.
• Remote mode: support connecting to the remote KWDB MCP Server.
• Improved optimization suggestions: enhance query optimization recommendations.
• Metrics resource: aAdd database metrics.

Contribution

Contributions are welcome! Please feel free to submit issues and pull requests.

License

This project is licensed under the MIT License.

Acknowledgements

• mark3labs/mcp-go - MCP Go server framework
• lib/pq - PostgreSQL Go driver

Other

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