MCP Resources

Resources provide read-only access to PostgreSQL system information. Resources are accessed via the read_resource tool or through MCP protocol resource methods.

Disabling Resources

Individual resources can be disabled via configuration to restrict what the LLM can access. See Enabling/Disabling Built-in Features for details.

When a resource is disabled:

• It is not advertised to the LLM in the resources/list response
• Attempts to read it return an error message

Available Resources

pg://database/schema

Returns a lightweight overview of all tables in the database. This resource provides quick discovery of what tables exist without the detailed column information from the get_schema_info tool.

Access: Read the resource to view database table listing.

Output: JSON object with table information:

{
  "tables": [
    {
      "schema": "public",
      "table": "users",
      "owner": "postgres"
    },
    {
      "schema": "public",
      "table": "products",
      "owner": "postgres"
    },
    {
      "schema": "analytics",
      "table": "events",
      "owner": "analytics_user"
    }
  ],
  "count": 3
}

Fields:

• tables: Array of table information objects
• schema: Schema name containing the table
• table: Table name
• owner: Table owner (role)
• count: Total number of tables returned

Note: System catalogs (pg_catalog, information_schema) are excluded from the listing.

Use Cases:

• Quick discovery of what tables exist in the database
• Get an overview of table organization by schema
• Identify table ownership for permission management
• Use as a starting point before calling get_schema_info for detailed column information

When to Use Resource vs Tool:

• Use this resource (pg://database/schema) when you need a quick overview of table names
• Use the tool (get_schema_info) when you need detailed column information, data types, constraints, and descriptions

pg://system_info

Returns PostgreSQL version, operating system, and build architecture information. Provides a quick and efficient way to check server version and platform details without executing natural language queries.

Access: Read the resource to view PostgreSQL system information.

Output: JSON object with detailed system information:

{
  "postgresql_version": "15.4",
  "version_number": "150004",
  "full_version": "PostgreSQL 15.4 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 11.2.0, 64-bit",
  "operating_system": "linux",
  "architecture": "x86_64-pc-linux-gnu",
  "compiler": "gcc (GCC) 11.2.0",
  "bit_version": "64-bit"
}

Fields:

• postgresql_version: Short version string (e.g., "15.4")
• version_number: Numeric version identifier (e.g., "150004")
• full_version: Complete version string from PostgreSQL version() function
• operating_system: Operating system (e.g., "linux", "darwin", "mingw32")
• architecture: Full architecture string (e.g., "x86_64-pc-linux-gnu", "aarch64-apple-darwin")
• compiler: Compiler used to build PostgreSQL (e.g., "gcc (GCC) 11.2.0")
• bit_version: Architecture bit version (e.g., "64-bit", "32-bit")

Use Cases:

• Quickly check PostgreSQL version without natural language queries
• Verify server platform and architecture
• Audit server build information
• Troubleshoot compatibility issues

Accessing Resources

Resources can be accessed in two ways:

1. Via read_resource Tool

{
  "uri": "pg://database/schema"
}

Or list all resources:

{
  "list": true
}

2. Via Natural Language (Claude Desktop)

Simply ask Claude to read a resource:

Database Schema:

• "Show me the output from pg://database/schema"
• "What tables are in the database?" (uses pg://database/schema)
• "List all tables" (uses pg://database/schema)

System Information:

• "Show me the output from pg://system_info"
• "What's the current PostgreSQL version?" (uses pg://system_info)
• "What version of PostgreSQL is running?" (uses pg://system_info)