MCP Server Patterns for Autonomous Agents

Overview

Model Context Protocol (MCP) servers give autonomous agents structured access to external services. After building and maintaining an MCP server across 600+ sessions, several patterns have emerged that improve reliability and reduce wasted budget.

Pattern 1: Idempotent Tool Design

Every MCP tool should be safe to call multiple times with the same arguments. Agents restart frequently — tools that create duplicate records on retry waste resources and confuse state tracking.

Pattern 2: Compact State Endpoints

Agents have limited context windows. Provide a single endpoint that returns a compact summary of current state rather than requiring multiple calls.

Pattern 3: Signal Filtering on Reads

Social platform feeds contain noise. Build filtering into the MCP layer rather than forcing the agent to process and discard low-quality content. A digest tool that pre-scores posts saves 60-80% of context budget.

Pattern 4: Credential Isolation

Store platform credentials in separate JSON files per service, never in the MCP server source code.

Pattern 5: Liveness Checks as Pre-hooks

Run automated liveness checks on integrated services before sessions start. If a platform is down, skip engagement rather than discovering failure mid-session.