McpSource.ListMcpToolsAsync

C# · package Toolnexus · SPEC §2 · McpSource.cs

public static Task<McpSource.McpInventory> ListMcpToolsAsync(object input, CancellationToken cancellationToken = default)

Connects to every enabled server, lists its tool definitions, and disconnects before returning — no toolkit, no ExecuteAsync wiring, nothing left running. The result is a plain McpInventory { Tools, Status }:

• Tools — server → IReadOnlyList<ToolInfo>, each ToolInfo(Name, Description, InputSchema) using the original, unprefixed tool name (not the server_tool name a connected McpSource would expose).
• Status — server → "connected" | "disabled" | "failed", same vocabulary as LoadAsync.

The returned inventory is unfiltered by any per-server tools allowlist — it exists to author or validate that allowlist, so it needs to see everything a server offers.

When to use it

Building a config UI or a CLI that shows “here’s what mcp.json would give you” without paying for a live toolkit. Also the right call for authoring a per-server tools allowlist: list first, see the real names, then write the allowlist against them.

Why this and not the alternative

Use LoadAsync when you actually want to call the tools

ListMcpToolsAsync never leaves a connection open — every client it opens is disposed before the method returns. Reach for McpSource.LoadAsync when you intend to execute tools, not just inventory them.

Examples

1. A disabled server never connects, and reports no tools

using Toolnexus;

var config = new Dictionary<string, object?>
{
    ["mcpServers"] = new Dictionary<string, object?>
    {
        ["docs_demo"] = new Dictionary<string, object?>
        {
            ["type"] = "local",
            ["command"] = new[] { "echo", "hi" },
            ["enabled"] = false,
        },
    },
};

var inventory = await McpSource.ListMcpToolsAsync(config);

if (inventory.Status["docs_demo"] != "disabled") throw new Exception(inventory.Status["docs_demo"]);
if (inventory.Tools.ContainsKey("docs_demo")) throw new Exception("a disabled server has no tool list");

Console.WriteLine($"ok: {inventory.Status["docs_demo"]}");

2. A server that can’t spawn is “failed”, not fatal

using Toolnexus;

var config = new Dictionary<string, object?>
{
    ["mcpServers"] = new Dictionary<string, object?>
    {
        ["broken"] = new Dictionary<string, object?>
        {
            ["type"] = "local",
            ["command"] = new[] { "toolnexus-docs-nonexistent-binary-xyz" },
            ["timeout"] = 2_000,
        },
    },
};

var inventory = await McpSource.ListMcpToolsAsync(config);

if (inventory.Status["broken"] != "failed") throw new Exception(inventory.Status["broken"]);
if (inventory.Tools.ContainsKey("broken")) throw new Exception("a failed server has no tool list");

Console.WriteLine($"ok: {inventory.Status["broken"]}");

3. Inventory the shared fixture, gated for a hermetic run

using Toolnexus;

var repo = Environment.GetEnvironmentVariable("TOOLNEXUS_REPO") ?? ".";
var fixture = Path.Combine(repo, "examples", "mcp.json");

// Parse the real fixture, then gate every server off so this doc example never dials out —
// the shape (parse -> gate -> inventory) is what an "author the allowlist" tool would run.
var config = McpSource.ParseConfig(fixture);
foreach (var (_, value) in config)
    ((IDictionary<string, object?>)value!)["enabled"] = false;

var inventory = await McpSource.ListMcpToolsAsync(config);

if (inventory.Status.Values.Any(s => s != "disabled"))
    throw new Exception($"unexpected: {string.Join(",", inventory.Status.Values)}");
if (inventory.Tools.Count != 0) throw new Exception("no server connected, so no tool lists");

Console.WriteLine($"ok: {string.Join(", ", inventory.Status.Keys.OrderBy(k => k))} all disabled");

Fields

Field	Type	What it is
McpInventory.Tools	IReadOnlyDictionary<string, IReadOnlyList<ToolInfo>>	Per-server tool defs, unfiltered by any allowlist.
McpInventory.Status	IReadOnlyDictionary<string, string>	server → "connected" | "disabled" | "failed".
ToolInfo.Name	string	The original, unprefixed MCP tool name.
ToolInfo.Description	string
ToolInfo.InputSchema	IDictionary<string, object?>	The built JSON-Schema object (same shape LoadAsync uses).

See also

• McpSource.LoadAsync — Read an mcp.json, connect every local stdio and remote streamable-HTTP server, expose each server tool as a Tool.
• McpSource.LoadAsync — The ctx-aware load: bound connection time and cancel a slow or hung server without leaking a child process.
• McpSource.ParseConfig — Parse and validate config without connecting — the fast fail for a malformed or misspelled server block.
• McpSource.ElicitationToRequest — Map an MCP server’s elicitation request onto the §10 suspension contract, and map the answer back.