ai-elements-core/dev.ai.elements.core.mcp/McpClient

McpClient

class McpClient(val url: String, headers: Map<String, String> = emptyMap(), auth: McpAuth? = null, http: OkHttpClient = DefaultHttpClient, clientInfo: McpImplementation = McpImplementation("ai-elements-kotlin", "0.3.0"), capabilities: JsonObject = JsonObject(emptyMap()))(source)

A Model Context Protocol client over the Streamable HTTP transport.

It speaks the current revision (MODERN_VERSION, stateless: every request carries its protocol version, client info and capabilities in _meta, and the MCP-Protocol-Version, Mcp-Method, Mcp-Name and Mcp-Param-* headers mirror them) and falls back to the legacy, session-based revisions (initialize handshake, Mcp-Session-Id) when the server turns out to be one — the "dual-era" client of the spec. The era is detected on the first request and cached. The deprecated HTTP+SSE transport is not supported.

Each request is its own POST; the reply is a JSON object or an SSE stream carrying notifications/progress before the response. Cancelling the calling coroutine closes the stream, which is the cancellation signal.

It declares elicitation (form and URL modes): a server that needs the user's input mid-call — InputRequiredResult on 2026-07-28 (SEP-2322: the client asks, then retries with inputResponses and the echoed requestState), elicitation/create on a legacy session stream — is answered through callTool's onInput; without one the answer is cancel. Sampling and roots are not declared. capabilities can add extensions, e.g. McpApps.CLIENT_CAPABILITIES for MCP Apps.

Parameters

headers

sent with every request, e.g. a static API key header.

auth

supplies (and refreshes) bearer tokens; see McpAuth.

Constructors

McpClient

constructor(url: String, headers: Map<String, String> = emptyMap(), auth: McpAuth? = null, http: OkHttpClient = DefaultHttpClient, clientInfo: McpImplementation = McpImplementation("ai-elements-kotlin", "0.3.0"), capabilities: JsonObject = JsonObject(emptyMap()))

Types

Companion

object Companion

Properties

instructions

@Volatile

var instructions: String?

Usage hints the server gives the model, if any.

protocolVersion

val protocolVersion: String?

The negotiated protocol version, once known.

serverInfo

@Volatile

var serverInfo: McpImplementation?

Name and version the server reported (legacy initialize or server/discover).

url

val url: String

Functions

callTool

suspend fun callTool(tool: McpTool, arguments: JsonObject, onInput: McpInputHandler? = null, onProgress: suspend (McpProgress) -> Unit? = null): McpToolResult

Call tool with arguments. onProgress receives the server's progress notifications while it runs.

suspend fun callTool(name: String, arguments: JsonObject, onInput: McpInputHandler? = null, onProgress: suspend (McpProgress) -> Unit? = null): McpToolResult

Call a tool by name (no x-mcp-header mirroring; prefer the McpTool overload).

suspend fun close()

Ends a legacy session (DELETE); a no-op for the stateless revision.

getPrompt

suspend fun getPrompt(name: String, arguments: Map<String, String> = emptyMap()): List<Pair<String, McpContent>>

Render prompt name; returns its messages as (role, content) pairs.

listPrompts

suspend fun listPrompts(): List<McpPrompt>

listResources

suspend fun listResources(): List<McpResource>

listTools

suspend fun listTools(): List<McpTool>

All tools, following pagination. Tools with invalid x-mcp-header annotations are dropped, as the spec requires.

readResource

suspend fun readResource(uri: String): List<McpContent.Resource>

The contents of the resource at uri (text and/or base64 blobs).