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Thirty teams at a bank are building agents. Design the gateway every model call, MCP tool call and agent-to-agent request goes through.

Most answers draw an API gateway with OAuth and stop. The bank's problem is the hop from agent to tool: whose identity reaches the CRM, which of 40 tools this agent may call, what stops a runaway loop, and what happens when the gateway itself is down.

Updated Oct 2026 · Grounded in real Forward Deployed Engineer interview loops and written to a senior-engineer editorial bar.

Most answers draw an API gateway with OAuth and stop. The bank's problem is the hop from agent to tool: whose identity reaches the CRM, which of 40 tools this agent may call, what stops a runaway loop, and what happens when the gateway itself is down.

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