Magentic Marketplace: buyer agents steered by fake credentials and prompt injection
- Entry
- AGT-007
- When
- November 2025
- Type
- Demonstration
- Evidence
- D Grade D
- Lost
- Simulated money
- Who
- Microsoft research simulation
- The agent
- 100 customer agents and 300 business agents
- Its authority
- Buyer agents chose sellers and paid
- How it was gamed
- Fake credentials, fake reviews and prompt injections worked on several models, and prompt injections were effective at steering payments to manipulative agents. Most models took the first ‘good enough’ offer.
- What was lost
- Simulated money.
- The design gap
- Buyer agents couldn’t verify sellers’ claims, and treated seller content as instructions.
- Principles
- Evidence
- Grade D. Research simulation.
Cite this entry: Monetal Labs, Gamed AI Agents Register v0.2, entry AGT-007. https://monetalabs.io/register/agt-007