32600 error code when trying to connect to mcp with openai responses API

### Describe the bug

I have been trying to use the githup-mcp as tool in the openai responses API and I seem to be connecting but keep getting

`"error": {
"type": "mcp_protocol_error",
"code": 32600,
"message": "Session terminated"
},`

even with simple calls such as return 5 most recent issue from a particular repo

### Current code running
```
const resp = await client.responses.create({
model: session.model,
temperature: 0,
parallel_tool_calls: false,
input: [
{ role: "system", content: [{ type: "input_text", text: "Exactly one MCP tool call; no optional fields." }] },
{ role: "user", content: [{ type: "input_text", text:
'Call "list_issues" and return the 5 most recent issues with exactly: {"query":"repo:github/github-mcp-server"}'
}] },
],
tools: [
{
type: "mcp",
server_label: "github",
server_url: "https://api.githubcopilot.com/mcp/",
headers: {
Authorization: `Bearer ${process.env.GITHUB_READ_ONLY_API_KEY}`,
},
require_approval: "never",
allowed_tools: [
"search_repositories",
"search_issues",
"get_issue",
"list_issues",
],
}
],
max_output_tokens: 200,
});
```
Any tips or help would be greatly appreciated have been trying all kinds of types of inputs and nothing is working. Thanks.

No repository file or test is named. Reproduce the shown OpenAI Responses API request against https://api.githubcopilot.com/mcp/ with the listed tools, then trace the MCP session termination producing code 32600. Done means identifying the compatibility or request issue and verifying that the same request no longer terminates the session.

Rédigé par le modèle d'indexation à partir du texte de l'issue.