Roots are a concept in MCP that define the boundaries where servers can operate. They provide a way for clients to inform servers about relevant resources and their locations.

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What are Roots?

A root is a URI that a client suggests a server should focus on. When a client connects to a server, it declares which roots the server should work with. While primarily used for filesystem paths, roots can be any valid URI including HTTP URLs. For example, roots could be: 
file:///home/user/projects/myapp
https://api.example.com/v1

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Why Use Roots?

Roots serve several important purposes:
  1. Guidance: They inform servers about relevant resources and locations
  2. Clarity: Roots make it clear which resources are part of your workspace
  3. Organization: Multiple roots let you work with different resources simultaneously

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How Roots Work

When a client supports roots, it:
  1. Declares the roots capability during connection
  2. Provides a list of suggested roots to the server
  3. Notifies the server when roots change (if supported)
While roots are informational and not strictly enforcing, servers should:
  1. Respect the provided roots
  2. Use root URIs to locate and access resources
  3. Prioritize operations within root boundaries

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Common Use Cases

Roots are commonly used to define:
  • Project directories
  • Repository locations
  • API endpoints
  • Configuration locations
  • Resource boundaries

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Best Practices

When working with roots:
  1. Only suggest necessary resources
  2. Use clear, descriptive names for roots
  3. Monitor root accessibility
  4. Handle root changes gracefully

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Example

Here’s how a typical MCP client might expose roots: 
{
  "roots": [
    {
      "uri": "file:///home/user/projects/frontend",
      "name": "Frontend Repository"
    },
    {
      "uri": "https://api.example.com/v1",
      "name": "API Endpoint"
    }
  ]
}
This configuration suggests the server focus on both a local repository and an API endpoint while keeping them logically separated.