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Core ConceptClient Capability / Access Control Layer

MCP Roots

Industry Definition Set • Entity Resolution Path: /glossary/mcp-roots

Quick Answer / TL;DR

URI-based boundary declarations from the client that tell the server which file system locations or namespaces the client has granted access to.

Key Takeaways

  • Client-declared access boundaries for filesystem or namespace resources.
  • Prevents servers from reading files outside the agreed scope.
  • Sent during the client's initialize request.
  • Essential for secure filesystem MCP integrations.
Definitive Statement: URI-based boundary declarations from the client that tell the server which file system locations or namespaces the client has granted access to.

Technical Context & Protocol Usage

Detailed Explanation
Roots prevent MCP servers from accessing files outside an agreed-upon boundary. The client sends a list of root URIs (e.g., `file:///Users/alice/projects`) during initialization. The server must respect these boundaries when exposing resources or executing tools. This is a critical security control for filesystem MCP servers.

Format & Payload Metadata

Format: List of root URI strings

Latency: Evaluated at initialization; minimal ongoing overhead

Real-World Implementation Use Case

Claude Desktop declares `file:///Users/alice/work` as its only root, so a filesystem MCP server cannot read `file:///Users/alice/private`.

M
MCPserver.in Engineering

Platform Team

Published: 2026-07-20
Updated: 2026-07-20

References & Technical Specifications

Cite This Page

MLA Style:

MCPserver.in Engineering. "MCP Roots." MCPserver.in Knowledge Hub, 20 July 2026, mcpserver.in/glossary/mcp-roots.