mbentham/SqlAugur

**An MCP server that gives AI assistants safe, read-only access to SQL Server databases. Every query is parsed into a full AST using Microsoft's official T-SQL parser — not regex — so comment injection, string literal tricks, and encoding bypasses are blocked at the syntax level.**
Quick Start
Use this order for all install methods:
1. Install SqlAugur
2. Save appsettings.json in the correct location
3. Add SqlAugur to your MCP client config
4. Verify by asking your assistant to call list_servers
Start with Installation for exact commands and file paths.
Why This Approach
- **AST-level query validation** — Most MCP database servers use keyword blocking or no validation at all. This project parses every query into a full syntax tree using Microsoft's official TSql180Parser. Comment injection, string literal tricks, and encoding bypasses are blocked at the syntax level, not with fragile regex patterns.
- **Rate limiting** — Token bucket throughput limiting and concurrency control prevent runaway AI query loops from overwhelming production SQL Servers. No other MCP database server offers this.
- **DBA diagnostic tooling** — Integrated support for First Responder Kit, DarlingData, and sp_WhoIsActive with parameter blocking that prevents write operations. This is an entirely new MCP capability category.
- **Response size optimisation** — DBA tools exclude verbose columns (XML query plans, deadlock graphs, metric breakdowns) and truncate long strings by default, reducing response sizes by 90–99%. Use verbose and includeQueryPlans parameters to get full untruncated output when needed.
- **Progressive discovery** — Up to 31 tools organized into toolsets that load on demand. Only 6 core tools are exposed initially, keeping the AI's context window small and reducing token usage. Additional toolsets are discovered and enabled as needed.
Features
**Security**
- Read-only by design — only SELECT and CTE queries are permitted
- AST-based query validation using ScriptDom (not regex)
- Parameter blocking on all diagnostic stored procedures to prevent writes
- Concurrency and throughput rate limiting
**Database Tooling**
- Multi-server support — named connections to multiple SQL Server instances
- Schema overview — concise Markdown schema maps with PKs, FKs, constraints, and defaults
- Table documentation — Markdown descriptions of columns, indexes, foreign keys, and constraints
- ER diagram generation — PlantUML and Mermaid diagrams with smart cardinality detection
- Schema exploration — list programmable objects, view definitions, extended properties, dependency graphs
- Query plan analysis — estimated or actual XML execution plans
- DBA diagnostics — optional integration with First Responder Kit, DarlingData, and sp_WhoIsActive with automatic response size optimisation
- Progressive discovery — dynamic toolset mode reduces initial context window usage by exposing tools on demand
Installation
All methods produce the same MCP server. Follow this order: install, save config, wire client, verify.
NuGet Global Tool (recommended)
**1. Install** (prerequisite: .NET 10.0 runtime)
**2. Save config file**
Example appsettings.json to save at that location:
**3. Add to MCP client**
To update: dotnet tool update -g SqlAugur
Docker / Podman
**1. Run SqlAugur container**
> **Note:** To reach a SQL Server on the host machine, use host.docker.internal (Docker Desktop) or --network=host (Linux). Replace docker with podman — all commands are identical. The :Z flag on volume mounts is required for SELinux-enabled systems (Fedora, RHEL); Docker Desktop users on macOS/Windows can omit it.
If you mount a config file, save it as /path/to/appsettings.json and mount it to /app/appsettings.json.
**2. Add to MCP client**
Docker Compose
MCP client configuration:
Build from Source
**1. Build** (prerequisite: .NET 10.0 SDK)
**2. Save config file**
**3. Add to MCP client**
Verify the MCP connection (LLM-first)
After restarting your MCP client, ask the assistant:
- Call list_servers
- Call list_databases for server "production"
Expected result:
- list_servers returns your configured server name (for example production)
- list_databases returns a JSON array of databases, not a connection or authentication error