The era of foundation models has revolutionized AI research, yet Graph Foundation Models (GFMs) remain constrained by the scarcity of large-scale graph corpora. We introduce GraphMaster — the first multi-agent framework specifically designed for graph data synthesis in data-limited environments. GraphMaster orchestrates four specialized LLM agents (Manager, Perception, Enhancement, and Evaluation) that collaboratively optimize the synthesis process through iterative refinement, ensuring both semantic coherence and structural integrity.
Graph Foundation Models face a critical data bottleneck. Existing synthesis methods fail for three reasons: (1) classical augmentation (GraphSmote, G-Mixup) only manipulates structure, producing semantically empty nodes; (2) LLMs cannot process entire graphs within context windows; (3) uncoordinated LLM generation introduces hallucinations that violate graph topology.

GraphMaster decomposes graph synthesis into four specialized agents:
Evaluated on 6 data-limited benchmarks with 4 GNN architectures (GCN, JKNET, GraphSage, GAT) on 8x A100 GPUs using QwQ-32B as the base LLM.

GraphMaster consistently outperforms all baselines across all datasets. The bottom row (blue) shows GraphMaster achieving the highest accuracy and F1 scores on every benchmark.

The synthesized graphs maintain high fidelity: KS statistic 0.357 (p=0.059) for degree distribution, 0.835 clustering coefficient similarity, and 0.988 label homogeneity — indicating near-perfect structural preservation.

Removing the Evaluation Agent causes the largest performance drop, confirming the critical role of iterative quality control. Each agent contributes uniquely to the final synthesis quality.