The first MCP demo usually proves that an agent can call a tool. The production problem begins after that. Enterprise tasks involve sequences: retrieve a record, inspect policy, update a field, generate a message, log the decision. Each step changes what the next step means.
Session integrity is the discipline of preserving that chain. The system should know which tool outputs informed which decisions, which state transitions occurred, and whether later calls remained consistent with earlier evidence. Many failures are not single bad calls; they are cross-tool contradictions.
MCP-based agents should be monitored as execution graphs. Calls, arguments, outputs, permissions, and state changes need to be replayable. Without that graph, debugging becomes narrative reconstruction rather than engineering.