MCP (Model Context Protocol) servers are that guide—directing LLMs to the right information, whether through broad, flexible access (generic) or targeted, optimized interactions (domain-specific). But how do you decide which approach is best for your use case?
Understanding MCP server designs
MCP (Model Context Protocol) servers are specialized interfaces that allow Large Language Models (LLMs) to connect with external data sources, services, or tools. They transform natural language instructions into actionable queries, providing LLMs with structured, efficient access to information.
MCP servers can be categorized into two main types:
- Generic MCP Servers: Highly flexible, adaptable to any database or tool, but requiring LLMs to understand and navigate complex schemas.
- Domain-Specific MCP Servers: Purpose-built for a specific domain, offering predefined tools that simplify interactions.
Generic MCP servers: a flexible starting point
Generic MCP servers are versatile, one-size-fits-all solutions. They connect LLMs to any database or tool without prior knowledge of their structure. This flexibility makes them quick to deploy, but it also means that LLMs must navigate and understand complex schemas on their own.
What makes an MCP server generic?
- Universal Querying: Accepts raw queries (like SQL) from the LLM, making it compatible with any database.
- Schema Agnostic: No predefined knowledge of database structure.
- Minimal Configuration: Quick to set up without extensive preparation.
Example: PostgreSQL MCP server with single query tool
A practical example of this approach is the @modelcontextprotocol/server-postgres. This MCP server connects LLMs to PostgreSQL databases with a single, flexible endpoint:
- Endpoint: POST /query – Accepts raw SQL queries directly from the LLM.
- Functionality: Allows LLMs to query any PostgreSQL database without knowing its schema in advance.
Pros and cons of generic MCP servers
✅ Advantages
- Fast and easy setup.
- Compatible with any database.
- No need to update for schema changes.
❌ Drawbacks
- High cognitive load for LLMs.
- Less efficient, requiring multiple queries.
- Security risks (SQL injection).
Domain-specific MCP servers: a tailored, efficient alternative
Domain-specific MCP servers are precision tools, purpose-built for a specific domain. They offer predefined tools that make interactions clear and efficient.
What makes an MCP server domain-specific?
- Predefined Tools: Provides intuitive commands like getMonsterByName or listMonstersByType.
- Schema Awareness: Knows the database structure and can optimize queries.
- Guided Interactions: LLMs use clear, named tools without exploring schema.
Example: custom PostgreSQL MCP server for RAGmonsters
A practical example is the Custom PostgreSQL MCP Server for RAGmonsters. It offers targeted tools:
- getMonsterByName: Fetches detailed information about a monster.
- listMonstersByType: Lists monsters of a given type.
Pros and cons of domain-specific MCP servers
✅ Advantages
- Easy, intuitive interactions for LLMs.
- Optimized for specific use cases.
- Secure (no raw SQL).
❌ Drawbacks
- Initial setup time.
- Less flexible to schema changes.
- Comparing the Two Approaches
| Aspect | Generic MCP Server | Domain-Specific MCP Server |
|---|---|---|
| Setup Speed | Fast, minimal configuration | Slower, requires planning |
| Efficiency | Lower, LLM must explore schema | High, optimized for specific tasks |
| Security | Risk of SQL injection | Secure, predefined tools |
| Flexibility | Adapts to any schema | Needs updates with schema changes |
| User Experience | Complex, LLM must learn | Simple, guided interactions |
Conclusion: choosing the right MCP server
To find out more and discover a concrete implementation of these concepts, discover how to create your MCP server with Otoroshi. It details how Otoroshi with LLM allows you to quickly create MCP servers and clients, expose functions via SSE, WebSockets or HTTP, and simplify integration with ready-to-use MCP connectors.
Whether you need a flexible, exploratory tool or a precise, optimized solution, understanding the difference between generic and domain-specific MCP servers will help you build smarter, more efficient LLM-powered applications. Choose a generic server for quick setup and adaptability, or a domain-specific server for secure, streamlined performance. Ready to start? Explore our PostgreSQL MCP Server or Custom RAGmonsters MCP Server to see both approaches in action.