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D1 MCP Server

MCP Server

Query D1 databases via Model Context Protocol

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Updated Jun 20, 2025

About

A Cloudflare Workers Durable Object that implements the MCP protocol, providing tools for SQL querying and schema introspection against a D1 database. Ideal for building LLM-powered data‑centric applications.

Capabilities

Resources
Access data sources
Tools
Execute functions
Prompts
Pre-built templates
Sampling
AI model interactions

MCP Server Demo

Overview

The Mcp With D1 Data server demonstrates how an MCP (Model Context Protocol) implementation can expose real‑world database content to an AI assistant. By leveraging Cloudflare’s D1 relational database and the , the server turns static data into a live, queryable resource that Claude or other LLMs can interact with in real time. This bridges the gap between generative AI and structured data, allowing developers to build applications that combine natural language reasoning with precise database operations.

Solving the Data Access Gap

Traditional AI assistants excel at generating text but often lack direct, authenticated access to external data stores. The MCP server solves this by providing a set of well‑defined tools that the LLM can invoke. The tool accepts SQL statements, while the tool exposes metadata about tables and columns. These tools give the assistant a controlled interface to read from, and potentially write to, the database—eliminating the need for custom API wrappers or manual data extraction. For developers, this means a single, consistent protocol to integrate any relational database into the AI workflow.

Core Features and Value

  • Stateful Durable Object – The server runs as a Cloudflare Durable Object, preserving context across interactions and automatically hibernating when idle. This ensures consistent performance without the overhead of re‑initializing connections.
  • Server‑Sent Events (SSE) – Communication is built on SSE, providing low‑latency, real‑time updates to the client as queries execute or results stream back.
  • Schema Management – Migration scripts (, ) and seed data () are bundled in the repository, enabling rapid provisioning of a fully populated database for testing or demo purposes.
  • Extensibility – While the current implementation targets D1, the tool definitions can be adapted to any SQL‑compatible database with minimal changes, making the pattern reusable across projects.

Real‑World Use Cases

  1. Data‑Driven Chatbots – A customer support bot can query a product catalog or order history directly, delivering accurate answers without hard‑coded responses.
  2. Analytics Dashboards – An AI assistant can generate dynamic SQL queries to pull metrics, visualize trends, and even suggest optimizations based on schema introspection.
  3. Automated Reporting – Periodic reports can be composed by the LLM, executed against the database, and emailed or posted to collaboration tools automatically.
  4. Rapid Prototyping – Developers can spin up a local D1 instance, expose it via MCP, and test conversational flows that depend on live data without writing bespoke adapters.

Integration with AI Workflows

Once the MCP server is running, an LLM client can invoke tools using standard Model Context Protocol messages. The tool is invoked with a natural language prompt that the assistant translates into an SQL statement, while provides contextual information about table structures. The server’s SSE transport streams results back as the LLM processes them, enabling interactive dialogues that feel seamless to end users. This pattern keeps data security tight (since the server mediates all database access) while giving developers the flexibility to shape queries dynamically.

Unique Advantages

  • Zero‑Code Database Exposure – No need to write custom REST APIs; the MCP server exposes database operations through a declarative tool interface.
  • Built‑in State Management – Durable Objects handle session persistence, reducing boilerplate for developers who would otherwise manage state manually.
  • Rapid Deployment – The repository includes a full Cloudflare Workers configuration, allowing instant deployment to the edge with minimal setup.
  • Test‑First Development – Integration tests are bundled, encouraging a TDD approach that ensures tool reliability before scaling to production.

In summary, the Mcp With D1 Data server provides a turnkey solution for integrating relational data into AI assistants. It offers secure, stateful access, real‑time communication, and a clear path to extend the pattern beyond D1, making it an invaluable asset for developers building data‑centric conversational experiences.