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nxmcp - NexusDB MCP Server

An MCP (Model Context Protocol) server that enables AI assistants to interact with NexusDB databases. Built with Delphi, this server exposes NexusDB operations as MCP tools and resources.

Features

  • Dual Transport - HTTP and STDIO (for Claude Desktop and other MCP clients)
  • Query Execution - Run SELECT queries and retrieve results as JSON
  • Data Manipulation - Insert, update, and delete records
  • Schema Management - Create tables, add columns, manage indexes
  • Schema Metadata - Descriptions on tables/columns/indexes, field validators, defaults on existing columns, data policies, audit settings
  • Database Management - Switch databases and servers at runtime, list aliases
  • Discovery - List tables, view schemas, get table structures (including descriptions, defaults, validators, policies, audit, and referential-integrity references), list indexes
  • Utility - Count records, show query execution plan

Requirements

Configuration

On first run, nxmcp.ini is automatically created next to the executable with default values. Edit it to configure both the NexusDB connection and MCP server:

[Connection]
; NXserver host address
ServerHost=localhost
; NXserver port (default: 16000)
ServerPort=16000

[Database]
; Database alias as configured on the NXserver
AliasName=YourAlias
; Table passwords, comma separated (leave empty if not used)
TablePassword=

[Authentication]
; NexusDB username
Username=your_username
; NexusDB password
Password=your_password

[Options]
; Automatically connect on startup (1=yes, 0=no)
AutoConnect=1
; Connection timeout in milliseconds
Timeout=3000

[Server]
; MCP server configuration
Port=3000
Host=localhost
Name=nxmcp
Version=3.1.0.0
Endpoint=/mcp

[CORS]
; Cross-Origin Resource Sharing configuration
Enabled=1
; Comma-separated list of allowed origins
AllowedOrigins=http://localhost,http://127.0.0.1,https://localhost,https://127.0.0.1

[SSL]
; SSL/TLS configuration (optional)
Enabled=0
CertFile=
KeyFile=
RootCertFile=

Building

  1. Open Source/nxmcp.dpr in Delphi
  2. Ensure NexusDB components and the MCP library are in your search path
  3. Build the project (Ctrl+F9)

Running

HTTP Transport (default)

nxmcp.exe

The server starts on http://localhost:3000/mcp by default.

STDIO Transport

nxmcp.exe --stdio

Uses stdin/stdout for JSON-RPC communication. Required for Claude Desktop and other MCP clients that use the STDIO transport.

Available Tools

Query & Discovery

Tool Description Parameters
execute_query Run SELECT queries sql
get_table_schema Get table structure tableName

Data Manipulation

Tool Description Parameters
get_table_data Read table data with pagination tableName, maxRows?, offset?, orderBy?
insert_record Insert a new record tableName, data (JSON string)
update_records Update matching records tableName, data (JSON string), whereClause
delete_records Delete matching records tableName, whereClause
execute_sql Run INSERT/UPDATE/DELETE sql

Schema Management

Tool Description Parameters
create_table Create a new table tableName, columns (JSON array), description?
drop_table Delete a table tableName
copy_table Clone a table sourceTable, targetTable, copyData?
rename_table Rename a table oldName, newName
add_column Add a column tableName, columnName, columnType, size?, required?, description?, defaultValueType?, constantValue?, applyAt?, applyOnModify?, overwriteNonNull?
drop_column Remove a column tableName, columnName
modify_column Modify a column tableName, columnName, newType?, newSize?, newName?, required? ("true"/"false")
create_index Create an index tableName, indexName, columns, unique?
drop_index Remove an index tableName, indexName

Schema Metadata

Tool Description Parameters
set_table_description Set or clear the description (comment) on a table tableName, description
set_column_description Set or clear the description on a column tableName, columnName, description
set_index_description Set or clear the description on an index tableName, indexName, description
set_field_validator Add/remove a server-side validator on a column (minmax or nochange, or none to remove) tableName, columnName, validator, minValue?, maxValue?, minNull?, maxNull?
set_column_default Add, replace, or clear the default-value descriptor on an existing column tableName, columnName, defaultType (none/CurrentDateTime/CurrentUser/Constant), constantValue?, applyAt?, applyOnInsert?, applyOnModify?, overwriteNonNull?
set_data_policies Set/clear table-level data policies: deny insert/modify/delete and enforce min/max record counts tableName, clear?, denyInsert?, denyModify?, denyDelete?, minRecordCount?, maxRecordCount?
set_audit Enable/disable audit-trail logging and BLOB inclusion (requires a server-side audit monitor for rows to be recorded) tableName, clear?, useAudit?, includeBlobFields?

get_table_schema reads directly from the table's TnxDataDictionary and surfaces description, per-column descriptions/defaults/validators, per-index descriptions, data policies, audit settings, and (read-only) referential-integrity references. list_indexes also includes each index's description.

Table Maintenance

Tool Description Parameters
empty_table Delete all records (keeps structure) tableName
pack_table Compact table, reclaim deleted space tableName
reindex_table Rebuild an index tableName, indexName
recover_table Recover records from broken table tableName
change_password Change table password tableName, oldPassword, newPassword
get_autoinc_value Get next auto-increment value tableName

Transactions

Tool Description Parameters
batch_execute Execute multiple SQL in one transaction statements (JSON array), snapshot?

Utility

Tool Description Parameters
count_records Fast record count via metadata tableName
list_indexes List all indexes on a table tableName
explain_query Show query execution plan sql

Database Management

Tool Description Parameters
list_aliases List available database aliases on the server (none)
switch_database Switch to a different database alias aliasName, tablePassword?
switch_server Switch to a different NexusDB server serverHost, serverPort?, aliasName?, tablePassword?

Available Resources

URI Description
nexusdb://server Connection status and server info
nexusdb://tables List of all tables
nexusdb://schema Schema overview with record counts

Column Types

For create_table and add_column:

  • AutoInc - Auto-incrementing integer
  • ShortString - ANSI string (specify size)
  • WideString - Unicode string (specify size)
  • Integer - 32-bit integer
  • Int64 - 64-bit integer
  • Word - 16-bit unsigned
  • Byte - 8-bit unsigned
  • Boolean - True/False
  • Float - Double precision
  • Currency - Currency type
  • DateTime - Date and time
  • Date - Date only
  • Time - Time only
  • Blob - Binary data
  • Memo - Large text

Column Options (required, descriptions, defaults)

create_table, add_column, and modify_column can declare column metadata directly — no separate call needed:

  • Required / NOT NULL — create_table (per-column "required": true), add_column (required), modify_column (required: "true"/"false"). Making an existing column required can fail if records already hold null values.
  • AutoInc — use the AutoInc column type.
  • Descriptions — per-column description in create_table/add_column; a table-level description in create_table.
  • Default values — see below.

In create_table, each column object accepts an optional default object, e.g.:

{ "name": "CreatedAt", "type": "DateTime",
  "default": { "type": "CurrentDateTime", "applyOnInsert": true } }

Default Value Types

For add_column, create_table (per-column default.type), and set_column_default:

  • CurrentDateTime - Auto-populate with current timestamp
  • CurrentUser - Auto-populate with current user
  • Constant - Literal value (pass via constantValue)
  • none - Remove any existing default (set_column_default only)

Default behaviour can be tuned with applyAt (client/server/both), applyOnInsert, applyOnModify, and overwriteNonNull.

Statement Switches

Prefix SQL statements with switches to control execution:

Switch Syntax Purpose
#T #T 5000 Timeout in milliseconds
#I #I- Disable index optimization
#S #S- Disable query simplification
#L #L+ Enable query logging (used by explain\_query)
#B #B+ Force BLOB copying

Example: #T 10000 SELECT * FROM LargeTable WHERE Status = 'Active'

Example Usage

Create a table

{
  "name": "create_table",
  "arguments": {
    "tableName": "Customers",
    "description": "Customer master data",
    "columns": "[{"name":"ID","type":"AutoInc"},{"name":"Name","type":"ShortString","size":100,"required":true,"description":"Display name"},{"name":"Email","type":"ShortString","size":255},{"name":"CreatedAt","type":"DateTime","default":{"type":"CurrentDateTime","applyOnInsert":true}}]"
  }
}

Insert a record

{
  "name": "insert_record",
  "arguments": {
    "tableName": "Customers",
    "data": "{"Name":"John Doe","Email":"john@example.com"}"
  }
}

Query data

{
  "name": "execute_query",
  "arguments": {
    "sql": "SELECT * FROM Customers WHERE Name LIKE 'J%'"
  }
}

Integration with Claude Code

HTTP Transport

claude mcp add --transport http nxmcp http://localhost:3000/mcp

STDIO Transport

claude mcp add nxmcp -- /path/to/nxmcp.exe --stdio

Integration with Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "nxmcp": {
      "command": "C:\\path\\to\\nxmcp.exe",
      "args": ["--stdio"]
    }
  }
}

License

The MIT License (MIT)

Copyright (c) 2025 Dr. Pfau Fernwirktechnik GmbH

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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