MCP implementation guide
How to develop an MCP server that is safe to operate
A production-ready MCP server is a controlled interface to an owned system, not merely a list of callable functions. Start with the records it may read, define each permitted action and approval boundary, then require evidence that every tool call either completed inside that boundary or stopped with a useful receipt.
- Good fit
- Use this approach when an assistant needs repeatable access to business data or actions and the organization must retain ownership of credentials, policy, logs, and recovery.
- Pause when
- Do not begin with a custom server when a read-only export answers the question, an established connector already provides the exact boundary, or nobody owns the source system after launch.
Signals this guide applies
- The same manual lookup or action appears in more than one assistant session.
- Credentials, tenant identity, approvals, or audit evidence matter to the action.
- A failed call needs a defined retry, stop, or human handoff instead of a plausible chat response.
A bounded way to proceed
- 01
Name the source of truth
List the exact records, owners, identifiers, freshness rules, and privacy classes the server will expose. A resource should preserve source identity and timestamps so the model cannot mistake a cached description for live business state.
- 02
Design narrow tools
Give each tool one business job, an explicit input schema, bounded output, and a documented failure state. Separate read operations from writes, and keep irreversible or high-impact actions behind an approval that the server can verify.
- 03
Bind identity and authority
Decide whether access belongs to a person, workspace, service account, or customer tenant. Validate that identity at execution time, request the smallest OAuth scopes, and reject any action whose entity binding is missing or ambiguous.
- 04
Replay and hand off
Test successful, denied, missing-evidence, stale-data, duplicate, and unknown-action cases. Package the schemas, runbook, rollback path, and representative receipts so another operator can inspect the server without reverse-engineering its code.
Artifacts an operator can inspect
Tool and resource contract
A versioned catalog states what each primitive reads or changes, which identifiers it accepts, the scope it requires, and the structured result it returns.
Authority matrix
A compact policy names automatic actions, approval-required actions, blocked actions, and the owner who can change those rules.
Verification receipt set
Representative executions preserve source, request, decision, result, and failure evidence without leaking tokens or private record bodies.
Questions operators ask
What should an MCP server expose first?
Expose the smallest read-only resource that resolves a repeated business question. It gives operators a way to validate identity, data shape, freshness, and privacy before granting an assistant any ability to change an external system.
How many tools should the first MCP release include?
There is no useful universal count. Include only the tools needed to complete one named workflow, and require a distinct test and authority rule for each. A small complete path is easier to evaluate than a broad catalog with unclear ownership.
Who owns an MCP server after delivery?
The client should own the accounts, source data, credential relationships, policy choices, deployment access, logs, and recovery procedure. A delivery partner can maintain the implementation, but should not become an invisible authorization dependency.