MCP, tool calling, and what agent interoperability changes

For most of the last few years, connecting an agent to a business system meant writing bespoke glue for that agent and that system. Standardized tool protocols — the Model Context Protocol among them — change the economics of that work: a tool exposed once can be consumed by whatever runtime you adopt next, and swapping the runtime stops meaning rewriting every integration.

What genuinely improves

• Integration reuse. The connector to your CRM is written once and survives a change of framework.
• Portability. Runtime and model decisions become reversible, which materially reduces vendor lock-in.
• Consistent tool semantics. Typed schemas and structured errors, rather than each integration inventing its own conventions.

What gets harder

Lowering the cost of connection raises the cost of getting authorization wrong. When adding a tool is a configuration change, the number of tools an agent can reach grows quietly, and the permission surface grows with it. The discipline that matters shifts from integration engineering to access governance.

• Per-agent, per-task credentials rather than one shared identity across a fleet.
• A registry of which agent may call which tool, reviewed rather than accumulated.
• Provenance carried through tool results, so untrusted content stays marked as untrusted.
• Audit at the tool boundary, because that is the layer that stays constant while runtimes change.

The practical position

Adopt standard tool interfaces where they exist — the portability is real and the cost of doing so is low. Then spend the effort you saved on the permission model, because that is now the part that determines whether you can safely scale from three agents to thirty.