Class McpClient

Namespace

LMKit.Mcp.Client

Assembly

LM-Kit.NET.dll

Client for Model Context Protocol (MCP) servers over HTTP using JSON-RPC 2.0. Establishes a session (initialize then notifications/initialized), exposes the server’s tool catalog (tools/list), executes tool invocations (tools/call) and health checks (ping), and preserves the MCP session id across requests. Includes content negotiation fallbacks, retries for transient HTTP errors (408/429/5xx), and consistent surfacing of JSON-RPC errors to callers.

public sealed class McpClient : IDisposable

Inheritance

object

McpClient

Implements

IDisposable

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Constructors

McpClient(string, HttpClient)

Initializes a new instance of McpClient using a caller-provided HttpClient. The caller retains ownership and is responsible for the lifecycle of the provided client.

McpClient(string, TimeSpan?)

Initializes a new instance of McpClient with an internally owned HttpClient.

Properties

ClientInfoName

Gets or sets the clientInfo.name value sent in the initialize RPC. Defaults to LMKit.NET.

ClientInfoTitle

Gets or sets the clientInfo.title value sent in the initialize RPC. Defaults to LMKit MCP Client.

ClientInfoVersion

Gets or sets the clientInfo.version value sent in the initialize RPC. Defaults to 1.0.0.

InitialAccept

Gets or sets the initial Accept profile for requests. If the server responds with 406, the client automatically falls back: JsonOrEventStream → JsonOnly → Wildcard → Omit. Default is JsonOrEventStream.

OnAuthFailed

Callback invoked when an authentication failure is detected (HTTP 401/403). Parameter is the HTTP status code (401 or 403).

OnReceived

Callback invoked after an HTTP response is received. Parameters are the JSON-RPC method name, HTTP status code, and a truncated response body snippet.

OnSending

Callback invoked immediately before an HTTP request is sent. Parameter is the JSON-RPC method name (e.g., tools/list).

SessionId

Gets the most recently observed MCP session identifier, as provided by the server either via the Mcp-Session-Id response header or in the initialize response payload.

Tools

Gets the cached tool list returned by tools/list. If not yet fetched, this property synchronously fetches the list (blocking the current thread). Prefer using GetToolsAsync(CancellationToken) for asynchronous code paths.

UserAgent

Gets or sets the User-Agent string added to outgoing requests. Changing this updates the DefaultRequestHeaders immediately. Defaults to LMKitMCPClient/1.0.

Methods

Dispose()

Disposes managed resources held by the client. Safe to call multiple times.

GetToolsAsync(CancellationToken)

Retrieves the server’s tool catalog once via tools/list and caches it for future access.

Initialize(CancellationToken)

Synchronously ensures the MCP session is initialized and returns a clone of the JSON-RPC initialize response payload.

InitializeAsync(CancellationToken)

Ensures the MCP session is initialized. If already initialized, returns a clone of the cached initialize response. If not, performs initialize and then notifications/initialized, caching the session id and payload. All concurrent callers await the same initialization task.

RefreshTools(CancellationToken)

Synchronously clears the cached tool list and fetches a fresh catalog via tools/list.

RefreshToolsAsync(CancellationToken)

Clears the cached tool list and fetches a fresh copy from the server.

SetBearerToken(string)

Sets or clears the Bearer token used for authorization. Marking a new token invalidates the current session so the next call re-initializes with fresh headers.

Shutdown(CancellationToken)

Synchronously shuts down the client, clearing cached state, canceling in-flight requests, and (when owned) recreating the internal HttpClient so the instance can be reused.

ShutdownAsync(CancellationToken)

Gracefully shuts down the client: clears cached state, cancels pending requests, and recreates the owned HttpClient so the instance can be reused later.