MCP server isolation

A server compromise should not confer every tenant, tool and downstream system privilege.

01 / The operating case

What changes in a real workflow?

One compromised search server process runs alongside a billing tool and can reach the billing API with a shared service account.

Trace the authority boundary
  1. 01Client / task
  2. 02MCP server
  3. 03Tool call + arguments
  4. 04Downstream effect

02 / Decision contract

What the executor must check

Separate workloads and credentials by trust domain, constrain egress and secret access, and validate tenant and action at the billing executor.

InputPrincipal · task · action · target
DecisionGrant ancestry · policy · current state
ResultEnforce · record · verify outcome

03 / Failure and evidence

What goes wrong, and what can be proven?

Failure mode

A single broad server identity turns one tool compromise into billing control.

Evidence to retain

Keep workload identity, egress attempt, downstream denial and affected tenant scope.

04 / Canonical scope

Why this reference stands alone

Cross-tenant isolation concerns tenant data separation; this page owns workload containment.

Protocol or attack trace

Compromise containment

Sequence

Search server process is compromised and tries to use sibling billing server credentials.

Negative test

Search workload cannot read billing secret or reach billing API; billing executor also denies its identity.

Primary references

Read the underlying material

Architecture discussion

Choose one consequential action and make its boundary explicit.

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