Model Context Protocol

Wuwe implements MCP protocol version 2024-11-05 for exposing tools and context, consuming external servers, and aggregating multiple process servers behind one host.

Server

mcp_server supports:

• initialization and capability negotiation;
• tools, resources, resource templates, prompts, and roots;
• pagination;
• resource subscriptions and list-change notifications;
• logging and progress notifications;
• server-initiated sampling and elicitation requests when the client advertises them;
• request lifecycle tracking, timeouts, access policy, authentication context, and audit callbacks.

Minimal stdio server

struct echo_text {
  static constexpr std::string_view description = "Echo a text string.";
  std::string text;

  std::string invoke() const { return text; }
};

int main() {
  wuwe::tool_provider<echo_text> tools;

  wuwe::agent::mcp::mcp_server server({
    .name = "wuwe-example",
    .version = "0.1.0",
  });
  server.add_tool_provider(tools);

  wuwe::agent::mcp::mcp_stdio_transport transport;
  return transport.run_stdio(server);
}

The stdio transport accepts Content-Length framing and newline-delimited JSON-RPC, and responds with the framing used by the incoming request. Keep stdout reserved for protocol messages.

Resources, templates, prompts, image content, and typed tools are demonstrated in examples/src/mcp_stdio_example.cpp.

Clients and process hosting

Component	Responsibility
mcp_stdio_client	Client operations over caller-provided streams
mcp_process_client	Start and communicate with one MCP subprocess
mcp_host_runtime	Manage multiple process servers, config, health, restart, circuit breaking, async calls, snapshots, and events
mcp_gateway	Re-export tools, resources, and prompts from running hosted servers with namespaced identifiers

The host runtime can load server definitions from JSON files, initialize processes, call protocol methods, collect stderr, and expose operational snapshots. The host application owns the user interface, secret handling, process allowlist, and configuration distribution.

HTTP

mcp_http_transport adapts JSON-RPC requests to an MCP server. mcp_http_listener provides a cpp-httplib listener with configurable host, port, MCP path, health path, body limit, CORS policy, and authorization callback.

The listener binds to 127.0.0.1 by default and supports an ephemeral port. Treat broader network exposure as an application security decision; add authentication and transport security outside or around the listener as required.

Security and telemetry

mcp_access_policy can restrict tools and resources. mcp_auth_context carries host authentication data, and audit callbacks record access decisions.

Host events can be sent to:

• in-memory storage;
• JSON Lines;
• Prometheus text metrics;
• OpenTelemetry-style spans;
• fan-out sinks;
• the common Wuwe agent event sink.

Knowledge integration

knowledge_tool_provider can be registered with mcp_server to expose search_knowledge. The example knowledge_mcp_example.cpp combines a scoped knowledge retriever, an MCP tool, and a cited resource.

See Host compatibility for framing and configuration guidance.