The short answer
A multi-agent system is several specialised LLM agents working together under orchestration to complete complex jobs a single agent can't reliably finish. In 2026 the tech exists; the difference between demo and production is the plumbing: clear handoff rules, shared memory, evals across the graph, and tracing so you can see exactly where it broke.
Why single agents fail on real work
Most production value lives in workflows that cross roles and systems: "research this claim, draft the report, check compliance, file the ticket, notify the team." One agent loses context or confidence partway through. Multiple specialised agents + a supervisor or router pattern keeps each step narrow and reliable.
Core architecture patterns that work
- Router / dispatcher: one lightweight agent decides which specialist handles the next step.
- Supervisor + workers: central agent manages state, delegates, and validates outputs before proceeding.
- Graph / LangGraph-style: explicit nodes and edges with conditional branching and human-in-the-loop checkpoints.
Design the contracts between agents first — what data each receives and what "done" looks like for the handoff.
The production realities most teams skip
Retrieval and tools must be per-agent or shared cleanly. Add evals not just per agent but for the full workflow (golden traces, success rate, cost per run). Observability (tracing every decision, tool call and output) turns "it worked in testing" into "we can ship this".
Guardrails at every boundary. Rate limits. Fallbacks to humans on uncertainty. Cost controls — multi-agent multiplies token usage fast.
How we ship multi-agent systems at Softgen
We scope the narrowest valuable end-to-end workflow first, design the graph and tools during a paid Discovery Sprint (£4,950), build with evals and tracing from day one, then ship behind a flag. AI builds (including multi-agent) start from £18,000; a realistic 3-5 agent production system lands £35k–£85k. We use frontier models where they win, open models or smaller for cost, and always ground in your data.
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