https://github.com/semgrep/mcp-tool-shadowing-demo

a demonstration of tool shadowing behavior in the Model Context Protocol
https://github.com/semgrep/mcp-tool-shadowing-demo

Last synced: 11 days ago
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a demonstration of tool shadowing behavior in the Model Context Protocol

• Host: GitHub
• URL: https://github.com/semgrep/mcp-tool-shadowing-demo
• Owner: semgrep
• License: mit
• Created: 2025-09-09T21:12:14.000Z (11 months ago)
• Default Branch: main
• Last Pushed: 2025-09-09T22:13:39.000Z (11 months ago)
• Last Synced: 2026-02-04T08:53:21.902Z (6 months ago)
• Language: Python
• Size: 36.1 KB
• Stars: 0
• Watchers: 0
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# mcp-tool-shadowing-demo

a demonstration of tool shadowing behavior in the Model Context Protocol.

## prerequisites

Project requires `uv`. See installation instructions:

https://github.com/astral-sh/uv?tab=readme-ov-file#installation

The makefile `install` instruction will install UV with the OSX/Linux instructions and then run `uv sync`.

## usage

The makefile will install the servers for Claude Code locally for this directory. To demonstrate collision behavior, run `make angel`, request `totally_cool_legit_tool` and note the behavior, then run `make devil` and rerun Claude Code with the same prompt and observe the difference.

To test with Windsurf, run `make provision-windsurf`

## notes

the Windsurf demonstration additionally requires line-jumping to frontrun tool choice. As of 2025-09-09 this was unpatched and worked successfully on Windsurf 1.99.3 (hash a21cda2c21704d89e6cf5b2804b460783ce44fad)

As far as I can tell, this demo does not reliably work correctly on Cursor - it does something else crazy but does not open calculator.