MCP : Execution failed: Unexpected end of JSON input #390
Description
Describe the bug
I wrote an MCP server (written using github.com/modelcontextprotocol/go-sdk ) and configured it for Copilot CLI this way :
{
"mcpServers": {
"vosdroits": {
"type": "local",
"command": "docker",
"args": [
"run",
"-i",
"--rm",
"ghcr.io/guigui42/mcp-vosdroits:latest"
],
"tools": [
"*"
]
}
}
}When I ask copilot "je dois acheter une maison, que dois je faire ?" that should trigger the "list_life_events" tool from the MCP, but I get this error
Execution failed: Unexpected end of JSON input
2025-10-23T18:48:17.043Z [DEBUG] InitiatorHeaderProcessor: Setting X-Initiator to 'user'
2025-10-23T18:48:17.043Z [START-GROUP] Sending request to the AI model
2025-10-23T18:48:18.675Z [INFO] [log_19731e, x-request-id: "00000-31e76f6c-6adc-4a72-822a-35033713aaf4"] post https://api.enterprise.githubcopilot.com/chat/completions succeeded with status 200 in 1630ms
2025-10-23T18:48:18.678Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:18.889Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:18.901Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.024Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.054Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.080Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.085Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.255Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.256Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.278Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.428Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.452Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:19.459Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:20.026Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:20.037Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:20.145Z [DEBUG] StreamingChunkDisplay received chunk.
2025-10-23T18:48:20.170Z [DEBUG] response (Request-ID 00000-31e76f6c-6adc-4a72-822a-35033713aaf4):
2025-10-23T18:48:20.170Z [DEBUG] data:
2025-10-23T18:48:20.171Z [DEBUG] {
"usage": {
"completion_tokens": 71,
"prompt_tokens": 21498,
"prompt_tokens_details": {
"cached_tokens": 0
},
"total_tokens": 21569
},
"id": "msg_vrtx_017giE1d8xoTvJH9UGnHnsng",
"choices": [
{
"index": 0,
"finish_reason": "tool_calls",
"logprobs": null,
"message": {
"role": "assistant",
"content": "Je vais vous aider à trouver les informations sur les démarches pour acheter une maison en France.",
"refusal": null,
"tool_calls": [
{
"id": "toolu_vrtx_011QhtN6Dqnnz4AJ9ZM3u633",
"type": "function",
"function": {
"name": "vosdroits-list_life_events",
"arguments": ""
}
}
],
"parsed": null
}
}
],
"created": 1761245300,
"model": "claude-sonnet-4.5",
"object": "chat.completion"
}
2025-10-23T18:48:20.171Z [END-GROUP]
2025-10-23T18:48:20.172Z [DEBUG] Command threw error: Unexpected end of JSON input
SyntaxError: Unexpected end of JSON input
at JSON.parse (<anonymous>)
at W9 (file:///Users/guigui42/.nvm/versions/node/v23.5.0/lib/node_modules/@github/copilot/index.js:1830:1484)
at file:///Users/guigui42/.nvm/versions/node/v23.5.0/lib/node_modules/@github/copilot/index.js:2417:19399
at Array.map (<anonymous>)
at Object.onMessage (file:///Users/guigui42/.nvm/versions/node/v23.5.0/lib/node_modules/@github/copilot/index.js:2417:19340)
at fBt (file:///Users/guigui42/.nvm/versions/node/v23.5.0/lib/node_modules/@github/copilot/index.js:1948:3057)
at wPn (file:///Users/guigui42/.nvm/versions/node/v23.5.0/lib/node_modules/@github/copilot/index.js:2417:19114)
at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
at async Jul (file:///Users/guigui42/.nvm/versions/node/v23.5.0/lib/node_modules/@github/copilot/index.js:2417:16739)
The same MCP server works fine in Claude Desktop
Works in VS Code as well
Affected version
0.0.349 Commit: 3469b3e
Steps to reproduce the behavior
No response
Expected behavior
it should use the tool as expected and not fail with this error
Additional context
macOS
and was able to reproduce on Linux Mint