juglans 0.2.17

Compiler and runtime for Juglans Workflow Language
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# std/mcps.jg — MCP Server Management Library
#
# Auto-discover tools from MCP servers and route tool calls via fetch().
# Supports MCP StreamableHTTP protocol (initialize → session → tools/list).
#
# Usage:
#   libs: ["std/mcps.jg"]
#
#   [github]: mcps.MCP(name="github", url="http://localhost:3001/mcp")
#   [fs]: mcps.MCP(name="fs", url="http://localhost:3002/mcp")
#
#   # All tools:
#   [ask]: chat(tools=mcp_tools, on_tool=[mcps.handle])
#
#   # Per-server tools (selective):
#   [ask]: chat(
#     tools=mcps.tools("github") + mcps.tools("fs"),
#     on_tool=[mcps.handle]
#   )

# Connect to an MCP server: initialize → tools/list → convert to OpenAI schema → register
[MCP(name, url, token)]: {
  _auth_headers = if(default(token, "") != "", {"Authorization": "Bearer " + token, "Accept": "application/json", "Content-Type": "application/json"}, {"Accept": "application/json", "Content-Type": "application/json"})
  _init = fetch(url=url, method="POST", headers=_auth_headers, body=json({"jsonrpc": "2.0", "method": "initialize", "params": {"protocolVersion": "2024-11-05", "capabilities": {}, "clientInfo": {"name": "juglans", "version": "0.1"}}, "id": "init"}))
  _session = default(get(default(get(_init, "headers", {}), {}), "mcp-session-id", ""), "")
  _list_headers = if(_session != "", merge(_auth_headers, {"mcp-session-id": _session}), _auth_headers)
  discover = fetch(url=url, method="POST", headers=_list_headers, body=json({"jsonrpc": "2.0", "method": "tools/list", "id": "discover"}))
  _mcp_converted = map(get(get(discover.data, "result", {}), "tools", []), t => {"type": "function", "function": {"name": name + "." + get(t, "name", "unknown"), "description": get(t, "description", ""), "parameters": default(get(t, "inputSchema", null), get(t, "input_schema", {}))}})
  _mcp_url = merge(default(_mcp_url, {}), from_entries([[name, url]])), _mcp_token = merge(default(_mcp_token, {}), from_entries([[name, default(token, "")]])), _mcp_session = merge(default(_mcp_session, {}), from_entries([[name, _session]])), _mcp_registry = merge(default(_mcp_registry, {}), from_entries([[name, _mcp_converted]])), mcp_tools = default(mcp_tools, []) + _mcp_converted
}

# Get tools for a specific MCP server by name
[tools(name)]: {
  result = get(default(_mcp_registry, {}), name, [])
}

# Unified tool call handler — dispatches to the correct MCP server by name prefix.
# When on_tool=[mcps.handle], the engine passes name + arguments.
[handle(name, arguments)]: {
  _mcp_server = split(name, ".")[0], _mcp_tool = join(slice(split(name, "."), 1), ".")
  _session = get(default(_mcp_session, {}), _mcp_server, "")
  _headers = if(_session != "", {"Accept": "application/json", "Content-Type": "application/json", "mcp-session-id": _session}, {"Accept": "application/json", "Content-Type": "application/json"})
  _headers = if(get(_mcp_token, _mcp_server, "") != "", merge(_headers, {"Authorization": "Bearer " + get(_mcp_token, _mcp_server, "")}), _headers)
  _call = fetch(url=get(_mcp_url, _mcp_server, ""), method="POST", headers=_headers, body=json({"jsonrpc": "2.0", "method": "tools/call", "params": {"name": _mcp_tool, "arguments": arguments}, "id": "1"}))
  result = get(get(get(get(_call.data, "result", {}), "content", [{}]), 0, {}), "text", "")
}