When MCP server returns an image, the context is lost

Describe the Bug

I built a mcp tool that takes an ISF shader file, validates it, then renders a frame to give back to an agent. Tool is here: GitHub - jimcortez/isf-renderer-tool: Command line to help ai generate correct shaders

MCP config:

{
  "mcpServers": {
    "isf-shader-renderer": {
      "command": "isf-mcp-server",
      "args": ["--stdio"]
    }
  }
}

When I use this tool, it successfully calls the tool and gets a response with encoded images. However, when that response is given back, the chat loses all context and just returns observations about the project. It does not display the image, analyze the image, or give any errors.

Steps to Reproduce

Use the tool provided to validate and render the shader. See the commands run and return values. Then see the ai lose all previous context and give a generic summary of it’s prompt.

Expected Behavior

Should show the image in the chat window as well as be able to analyze the image itself.

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.2.4 (Universal)
VSCode Version: 1.99.3
Commit: a8e95743c5268be73767c46944a71f4465d05c90
Date: 2025-07-10T16:55:16.443Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Darwin arm64 23.5.0

Additional Information

Here is a simple shader you can use,

/*{
    "DESCRIPTION": "Every pixel is blue.",
    "CREDIT": "pyvvisf example",
    "ISFVSN": "2.0",
    "CATEGORIES": ["Generator"],
    "INPUTS": []
}*/
void main() {
    gl_FragColor = vec4(0.0, 0.5, 1.0, 1.0); // blue
}

Does this stop you from using Cursor

No - Cursor works, but with this issue

Are there any logs or anything I can pull to see the issue? Obviously cursor is having some issue dealing with the MCP result, but I can’t see where the crash is.

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