Your AI agent calls MCP servers. But do you know if those servers are reliable?
MCP (Model Context Protocol) is how agents talk to tools. There are 14,820+ MCP servers in the wild. Some are rock-solid. Some go down every hour. Some return garbage data. Your agent can't tell the difference — unless you add a trust check.
The Problem #
When your LangChain agent calls an MCP server:
- It doesn't know if the server has been reliable historically
- It doesn't know if the server is currently degraded
- If the server fails, your agent fails — with no fallback
The Fix: TrustGateInterceptor #
Using the interceptor pattern in langchain-mcp-adapters
:
from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain_mcp_adapters.trust_gate import TrustGateInterceptor
trust_gate = TrustGateInterceptor(min_trust_score=60)
async with MultiServerMCPClient(
{"my_server": {"url": "https://my-mcp.example.com/mcp", "transport": "streamable_http"}},
interceptors=[trust_gate],
) as client:
tools = client.get_tools()
Every tool call checks Dominion Observatory (14,820 servers tracked, 93K+ interactions observed) before executing. Servers below your threshold get blocked with an explanation.
What's Happening Under the Hood #
The trust gate calls the Observatory API before each tool invocation. It gets back:
Trust score(0-100) based on observed behavior across the ecosystem - Latency stats— avg and p95 - Success rate— what % of calls succeed - SLA grade— Platinum/Gold/Silver/Bronze/Unrated
If the server doesn't meet your threshold, the call is blocked and your agent gets a clear message explaining why. Scores are cached for 5 minutes to avoid excessive API calls.
The Interceptor Pattern #
The TrustGateInterceptor
implements LangChain's ToolCallInterceptor
protocol — the same pattern used for rate limiting, logging, and auth injection. It composes cleanly with other interceptors:
interceptors=[
trust_gate, # Check trust first
rate_limiter, # Then rate limit
audit_logger, # Then log
]
For Enterprise / MiCA Compliance #
If you're in the EU and need audit trails for MiCA Article 12 (enforcement July 1, 2026), the compliance tier returns signed attestation receipts at $0.10/query.
Links #
- Observatory: https://dominion-observatory.sgdata.workers.dev - GitHub: https://github.com/vdineshk/dominion-observatory - MCP endpoint: https://dominion-observatory.sgdata.workers.dev/mcp