Unable to use `--allow-tool` with `--prompt` and `--additional-mcp-config` (works only with `--yolo`)

## Unable to use `--allow-tool iot-local-debug` with `--prompt` and `--additional-mcp-config` (works only with `--yolo`)

### Description

When running `copilot.exe` (version 0.0.414) with the `--prompt` and `--additional-mcp-config` flags, I am not able to use the MCP `iot-local-debug` (defined in my `$mcp_config`). All attempts to allow the tool with `--allow-tool` (including different variations) fail, but using `--yolo` works.

Notably, when using `--interactive` mode instead of `--prompt`, `--allow-tool iot-local-debug` **works as expected**. This suggests the issue is specific to non-interactive (`--prompt`) mode.

---

### How to Reproduce

The MCP config:

```powershell
$mcp_config = '{"mcpServers":{"iot-local-debug":{"type":"http","url":"http://localhost:8080/mcp","headers":{},"tools":["*"]}}}'
```

The quick test script for `--prompt`:

```powershell
$p_quick = @'
IMPORTANT: You are ONLY allowed to use MCP tools for testing. Do NOT use direct REST API calls (curl, Invoke-RestMethod, etc.).

Use mcp iot-local-debug to interact with the local MCP server.

Quick Test: Generate Key Pair Only

Step 1: "Generate a key pair for my IoT device"
↓
MCP calls: generate_key_pair (no parameters needed)
↓
Expected: Receive {"upload_key": "...", "download_key": "..."}

CONSTRAINT: You MUST use only the MCP tool generate_key_pair from the iot-local-debug server.

Please execute the step using MCP tools only and confirm the expected outcome.
'@
```

The main command (**failing** with `--prompt`):

```powershell
& copilot.exe @(
"--prompt"
$p_quick
"--additional-mcp-config"
$mcp_config
"--model"
"gpt-5-mini"
"--allow-all-paths"
"--no-ask-user"
"--no-auto-update"
"--no-custom-instructions"
"--allow-tool"
"iot-local-debug"
"--allow-tool"
"iot-local-debug-generate_key_pair"
"--allow-tool"
"iot-local-debug(*)"
"--allow-tool"
"generate_key_pair"
# "--yolo" # Uncommenting this is the only thing that works
)
```

The equivalent command (**working** with `--interactive`):

```powershell
& copilot.exe @(
"--interactive"
"--additional-mcp-config"
$mcp_config
"--model"
"gpt-5-mini"
"--allow-all-paths"
"--no-ask-user"
"--no-auto-update"
"--no-custom-instructions"
"--allow-tool"
"iot-local-debug"
)
```

---

### Observed Behavior

All `--allow-tool` variations fail in `--prompt` mode and produce the following output:

```
(This may take a minute as the AI processes the request)

Running MCP iot-local-debug generate_key_pair to create an upload/download key pair for the IoT device using the local MCP tool. I'll also report intent "Generating keypair" alongside the MCP call.

✗ iot-local-debug-generate_key_pair
Permission denied and could not request permission from user

Requesting user's permission to allow MCP generate_key_pair because the MCP tool reported permission denied.
```

---

### Expected Behavior

Passing `--allow-tool iot-local-debug` (or any of the other variations) in `--prompt` mode should allow the MCP tool to execute, consistent with the behavior in `--interactive` mode — and without requiring `--yolo`.

---

### Workarounds

| Mode | `--allow-tool iot-local-debug` | `--yolo` |
|---|---|---|
| `--interactive` | ✅ Works | ✅ Works |
| `--prompt` | ❌ Permission denied | ✅ Works |

---

### Version

```
copilot --version
GitHub Copilot CLI 0.0.414
```

---

### Additional Context

- `$mcp_config` defines the `iot-local-debug` MCP server as an HTTP server at `http://localhost:8080/mcp` with a wildcard tools allowlist (`"tools": ["*"]`).
- The failure occurs regardless of which `--allow-tool` pattern is used in `--prompt` mode.
- `--yolo` works as a workaround, but is not desirable for security reasons.

---

### Questions / Possible Bug

- Is `--allow-tool` handled differently between `--prompt` and `--interactive` modes?
- Is the correct format for `--allow-tool` with MCP tools `-`, `()`, or something else entirely?
- Is there a known incompatibility between `--additional-mcp-config` and `--allow-tool` in `--prompt` mode?
- Why does `--yolo` succeed where explicit `--allow-tool` patterns do not in `--prompt` mode?
- Does the `"tools": ["*"]` wildcard in `$mcp_config` conflict with or get overridden by `--allow-tool` resolution?