| 1 | """Thin MCP SSE client helper. |
| 2 | |
| 3 | Uses the `mcp` Python SDK's sse_client transport to connect to an SSE MCP server, |
| 4 | call one tool, and return the raw text result. Falls back gracefully on any failure. |
| 5 | """ |
| 6 | from __future__ import annotations |
| 7 | |
| 8 | import asyncio |
| 9 | import json |
| 10 | from contextlib import asynccontextmanager |
| 11 | from typing import Any, AsyncGenerator |
| 12 | |
| 13 | import httpx |
| 14 | from mcp.client.sse import sse_client |
| 15 | from mcp import ClientSession |
| 16 | |
| 17 | |
| 18 | async def call_mcp_tool( |
| 19 | base_url: str, |
| 20 | tool_name: str, |
| 21 | arguments: dict[str, Any], |
| 22 | timeout: float = 3.5, |
| 23 | ) -> list[Any]: |
| 24 | """Call an MCP tool over SSE and return parsed content blocks. |
| 25 | |
| 26 | Each content block's text is JSON-parsed when possible. The result may be: |
| 27 | - A dict (e.g. {"total": N, "results": [...]} from CBM search_graph) |
| 28 | - A list (e.g. [...entities...] from memory-graph query_entities) |
| 29 | - A dict with "text" key (plain-text fallback when JSON parse fails) |
| 30 | |
| 31 | Returns empty list on any failure (timeout, connection error, parse error). |
| 32 | """ |
| 33 | try: |
| 34 | async with asyncio.timeout(timeout): |
| 35 | async with sse_client(base_url) as (read, write): |
| 36 | async with ClientSession(read, write) as session: |
| 37 | await session.initialize() |
| 38 | result = await session.call_tool(tool_name, arguments=arguments) |
| 39 | out: list[Any] = [] |
| 40 | for block in (result.content or []): |
| 41 | if hasattr(block, "text"): |
| 42 | try: |
| 43 | out.append(json.loads(block.text)) |
| 44 | except (json.JSONDecodeError, TypeError): |
| 45 | out.append({"text": block.text}) |
| 46 | return out |
| 47 | except Exception: |
| 48 | return [] |