Every governance story has the same unglamorous first chapter: you have to know what you are governing. For data it is classification. For agents it is the identity registry. For tools it is an approved registry of MCP servers and the tools they expose. Skip it, and every later control is built on sand, because policy cannot reason about a tool that nobody recorded.
The reason this matters with MCP specifically is that MCP makes tools easy to add. That is the point of it. But ease of addition without a register produces exactly the situation enterprises already know from the world of unsanctioned software: a sprawl of capabilities that no one is tracking, some of them powerful, some of them connected to sensitive systems, none of them reviewed. A registry is how you keep the convenience of MCP without inheriting that sprawl.
What a tool registry should record
A registry that is just a list of names is barely better than no registry. A useful one captures enough about each tool to make a governance decision.
It records the MCP servers themselves: what they are, where they run, and who stood them up. It records the tools each server exposes, because one server can offer many tools with very different risk profiles. It records ownership, a named person or team accountable for each tool, so that review and retirement have an address. It records versions, because a tool can change what it does between versions, and a control written against last quarter's behavior may not hold against this quarter's. It records the scopes and permissions each tool requires, so you can see how much standing access a tool carries. And it records a risk classification, so the system can treat a read-only lookup differently from an action that moves money or deletes data.
Risk classification is the part that earns its keep
Of those fields, risk classification is the one that does the most work later. The whole point of governance is to apply control in proportion to risk, and you cannot do that if every tool looks the same to the policy engine. A tool that reads public reference data needs little ceremony. A tool that can issue refunds or change production configuration needs scoped credentials, tight identity binding, and very likely a human approval before it runs.
Classifying tools by risk at registration is what lets all of those downstream controls be automatic and proportionate. The high-risk tool gets the heavy controls because it was flagged high-risk in the registry, and the low-risk tool stays frictionless because it was flagged low-risk. Without classification, you are forced to choose one posture for everything, and both choices are wrong.
The registry as the start of an AI bill of materials
There is a bigger idea the registry feeds into. Enterprises are increasingly expected to know what their AI systems are actually made of: which models, which data sources, which tools. That inventory is the AI bill of materials, and the tool registry is one of its core components. A maintained registry of MCP servers and tools is not just an operational nicety. It is part of being able to answer, credibly, the question "what can your AI do and what is it built from," which is a question regulators, customers, and your own risk function will all eventually ask.
Keeping it honest over time
A registry decays the moment it stops being maintained. Tools get added outside the process, versions change, owners move on. The registry has to be a living function tied into how tools are actually deployed, so that registration is part of bringing a tool online rather than a form someone fills in afterward and never updates. The same discipline that keeps a data classification honest applies here: it has to run as part of the workflow, every time, or it drifts away from reality.
Once the registry is in place and trustworthy, the rest of tool governance has its footing. Access can be bound to identity, calls can be scoped to purpose, which is the subject of scoped credentials, and every call can be logged against a known tool. The full architecture is in the complete guide to MCP governance, and the platform capability is MCP and tool governance.