Mastra agent-tool and MCP boundary

Evidence-backed facts

1. Mastra agents can use locally defined tools and tools discovered through configured MCP clients. informative
2. The Mastra runtime presents tool schemas to the model, executes selected local or MCP calls, and incorporates returned results. informative
3. MCP endpoints, transport credentials, local tool code, workspace access, and human approval for risky calls remain explicit configuration. informative
4. Tool discovery does not prove server trust, execution success, result correctness, production deployment, or authorization for side effects. informative

Primary sources