AI: MCP server tools not exposed with expected naming when using AvailableTools

[KnicKnic]

Bug

When SessionConfig.AvailableTools is set to a bare MCP server name (e.g. ["github-mcp-server"]) and the MCP server is configured via SessionConfig.McpServers as an HTTP remote server, the MCP server's tools are not surfaced with the expected <server>-<tool> naming convention. The model reports tools like read_file, edit_file, create_file, view_directory, ask_user instead of the expected github-mcp-server-actions_list, github-mcp-server-list_pull_requests, etc.

Versions

• SDK: GitHub.Copilot.SDK 0.1.33-preview.0
• CLI: GitHub Copilot CLI 1.0.5
• Runtime: .NET 8.0

Expected Behavior

When AvailableTools = ["github-mcp-server"] and the session has an McpRemoteServerConfig for "github-mcp-server" pointing to https://api.enterprise.githubcopilot.com/mcp/readonly, the model should see the 18 MCP tools with proper prefixed names:

github-mcp-server-actions_list, github-mcp-server-actions_get, github-mcp-server-get_job_logs,
github-mcp-server-list_pull_requests, github-mcp-server-search_pull_requests,
github-mcp-server-pull_request_read, github-mcp-server-list_issues, github-mcp-server-search_issues,
github-mcp-server-issue_read, github-mcp-server-list_commits, github-mcp-server-get_commit,
github-mcp-server-list_branches, github-mcp-server-search_code, github-mcp-server-search_repositories,
github-mcp-server-get_file_contents, github-mcp-server-search_users, github-mcp-server-list_copilot_spaces,
github-mcp-server-get_copilot_space

Actual Behavior

The model reports 9 tools with generic names that don't match the expected MCP tool naming convention:

read_file, edit_file, create_file, view_directory, powershell, grep, glob, ask_user, sql

None of the 18 expected github-mcp-server-* tools are visible.

Repro Output

MCP server: github-mcp-server
  Type: http
  URL:  https://api.enterprise.githubcopilot.com/mcp/readonly
  AvailableTools: ["github-mcp-server"]

Creating session with remote MCP server + AvailableTools...
Session created.

Asking model to list all its tools...

--- Model Response ---
read_file, edit_file, create_file, view_directory, powershell, grep, glob, ask_user, sql
--- End Response ---

Tools reported: 9 (ignoring skill, report_intent)
  - read_file
  - edit_file
  - create_file
  - view_directory
  - powershell
  - grep
  - glob
  - ask_user
  - sql

Expected MCP tools: 18
Found:   0
Missing: 18
Missing MCP tools:
  - github-mcp-server-actions_list
  - github-mcp-server-actions_get
  - github-mcp-server-get_job_logs
  - github-mcp-server-list_pull_requests
  - github-mcp-server-search_pull_requests
  - github-mcp-server-pull_request_read
  - github-mcp-server-list_issues
  - github-mcp-server-search_issues
  - github-mcp-server-issue_read
  - github-mcp-server-list_commits
  - github-mcp-server-get_commit
  - github-mcp-server-list_branches
  - github-mcp-server-search_code
  - github-mcp-server-search_repositories
  - github-mcp-server-get_file_contents
  - github-mcp-server-search_users
  - github-mcp-server-list_copilot_spaces
  - github-mcp-server-get_copilot_space

Self-Contained Repro Code

using GitHub.Copilot.SDK;

public class McpToolSpecified
{
    public async Task RunAsync(string cliPath)
    {
        var mcpServer = new McpRemoteServerConfig
        {
            Url = "https://api.enterprise.githubcopilot.com/mcp/readonly",
            Type = "http",
            Tools = new List<string> { "*" }
        };

        await using var client = new CopilotClient(new CopilotClientOptions { CliPath = cliPath });
        await client.StartAsync();

        var sessionConfig = new SessionConfig
        {
            Model = "gpt5-mini",
            McpServers = new Dictionary<string, object>
            {
                ["github-mcp-server"] = mcpServer
            },
            AvailableTools = new List<string> { "github-mcp-server" },
            OnPermissionRequest = PermissionHandler.ApproveAll,
        };

        await using var session = await client.CreateSessionAsync(sessionConfig);

        // Ask the model what tools it sees
        var done = new TaskCompletionSource();
        string? content = null;
        using var sub = session.On(evt =>
        {
            switch (evt)
            {
                case AssistantMessageEvent msg: content = msg.Data.Content; break;
                case SessionIdleEvent: done.TrySetResult(); break;
                case SessionErrorEvent err: done.TrySetException(new Exception(err.Data.Message)); break;
            }
        });
        await session.SendAsync(new MessageOptions
        {
            Prompt = "List every tool name you have access to. Output ONLY a comma-separated list."
        });
        await done.Task;

        Console.WriteLine($"AvailableTools: [github-mcp-server]");
        Console.WriteLine($"Model sees: {content}");
        // BUG: Model sees generic tool names, not github-mcp-server-* prefixed MCP tools
    }
}

Notes

• Without AvailableTools at all (just McpServers), the MCP tools also don't appear — model only sees core CLI tools (see separate McpToolDiscovery test).
• The tool names the model reports (read_file, edit_file, etc.) appear to be the CLI's own built-in tools with different naming, not the MCP server's tools.
• This suggests the CLI may not be connecting to the remote HTTP MCP server at all, or the AvailableTools bare server name is being interpreted as something else.