Byward – put any MCP server behind OAuth 2.1 and Entra ID

The Byward project launched Byward v0.1.0, an open-source authorization gate designed to place Model Context Protocol servers behind OAuth 2.1 with first-class Microsoft Entra ID integration. According to github.com's report, the software packages as a single Go binary configured through environment variables to shield HTTP and stdio MCP servers. Positioned between clients like Claude, ChatGPT, VS Code, or Cursor and backend tools, Byward handles authentication and issues separate short-lived access credentials, ensuring upstream servers never see client tokens or identity provider secrets.

This report covers the v0.1.0 architecture, client connection protocols, registration workflows, and container deployment requirements for systems engineers and enterprise AI developers. Permitting autonomous coding agents to access internal tools without structured identity boundaries introduces significant credential leakage risks. Byward resolves this vulnerability by decoupling identity verification from upstream tool logic, enabling engineering teams to govern tool access through Entra ID application roles, active directory groups, and automated token rotation without requiring modifications to existing Model Context Protocol server codebases.

What Byward – put any MCP server behind OAuth 2.1 shipped

The initial release of Byward establishes a dedicated authorization server that functions as a reverse proxy for upstream Model Context Protocol services over HTTP or stdio. Packaged as a single Go binary, the software utilizes SQLite for state storage and enforces rate limits across OAuth endpoints to protect against automated abuse. The runtime emits a structured audit stream and native Prometheus metrics for system monitoring. Operators can inspect configurations, network reachability, and secret bindings before directing live traffic using the built-in byward doctor command.

Access control mechanisms inside Byward connect directly to enterprise directory structures, allowing administrators to restrict tool execution based on Microsoft Entra ID application roles and security groups. When a client connects, Byward directs the user through an Entra sign-in flow, presents an intermediate consent interface, and signs short-lived authorization tokens. Refresh tokens cycle through built-in reuse detection to prevent replay attacks. Administrators also gain immediate revocation switches capable of invalidating access tokens for a specific user account or terminating sessions across the entire deployment.

What changed for builders in Byward – put any MCP server behind OAuth

Before Byward, connecting artificial intelligence assistants to custom MCP tools required hardcoding static credentials into configuration files or embedding authentication logic directly inside upstream services. Byward eliminates token handling from upstream servers by acting as an independent protocol gate that never passes client tokens to backend tools. Supported clients connect automatically using Client ID Metadata Documents or Dynamic Client Registration, while operators can establish static client configurations for remaining environments. This architecture replaces manual credential sharing with rotating, short-lived tokens validated against central enterprise directories.

Verification testing for Byward confirms broad compatibility across leading agent interfaces and official software development kits. Verified clients that sign in against real Entra tenants to execute tools include Claude Code, claude.ai, ChatGPT, VS Code, and Cursor version 3.29.9. In continuous integration test pipelines, the official TypeScript, Python, and Go MCP SDKs alongside the reference MCP Inspector run against Byward. This verified compatibility ensures that engineering teams building tool integrations can rely on standardized client registration mechanisms without writing custom authentication wrappers.

How to install or upgrade Byward – put any MCP server behind OAuth 2.1

Deploying Byward begins with staging configuration parameters and provisioning an application registration within Microsoft Entra ID. Operators can invoke the automated setup command to print required directory setup commands:

byward init entra

Once the Entra tenant identifier, application client credentials, and secrets are configured, administrators launch the official container image from GitHub Container Registry. The container executes under an unprivileged user while mounting local volumes for persistent SQLite state and read-only secrets:

docker run --rm -p 8080:8080 --user "$(id -u):$(id -g)" \
  -v "$PWD/byward-data:/var/lib/byward" \
  -v "$PWD/entra-client-secret:/run/secrets/entra-client-secret:ro" \
  -e BYWARD_PUBLIC_URL=https://mcp.example.com/mcp \
  -e BYWARD_UPSTREAM_URL=http://upstream.internal:3001/mcp \
  -e BYWARD_ENTRA_TENANT="$TENANT_ID" \
  -e BYWARD_ENTRA_CLIENT_ID="$APP_ID" \
  -e BYWARD_ENTRA_CLIENT_SECRET_FILE=/run/secrets/entra-client-secret \
  -e BYWARD_LISTEN=0.0.0.0:8080 \
  ghcr.io/byward-dev/byward:latest

Developers compiling from source or contributing pull requests use the mise development environment tool to manage project toolchains. Contributing workflows rely on mise to install Go, formatters, and static analysis linters before executing test suites:

mise install go golangci-lint go:golang.org/x/tools/cmd/goimports actionlint zizmor shellcheck go:github.com/google/go-licenses/v2
mise run check

Operators upgrading deployments should verify container images using cosign signatures, which contain cryptographically verified build provenance metadata. Teams can also run diagnostic checks against live instances to validate active configurations and network connectivity:

byward doctor

Gotchas and compatibility in Byward – put any MCP server behind OAuth

Teams evaluating Byward must consider its early lifecycle status, as version 0.1.0 is pre-1.0 software that has not undergone an independent third-party security audit. Production operators should review the project security posture documentation and follow the hardening checklist before exposing sensitive systems. Additionally, Byward does not terminate TLS connections directly, binding instead to unencrypted HTTP listeners. Ingress operators must position Byward behind a reverse proxy, load balancer, or ingress controller that handles TLS termination and forwards encrypted traffic to the listening port.

Client compatibility requires attention to specific application version thresholds across developer systems. While Cursor version 3.29.9 connects successfully using Dynamic Client Registration, earlier versions such as Cursor 2.6.22 fail to negotiate authentication with Byward. Administrators must also note that the main repository branch moves ahead of releases, requiring configuration settings to reference tagged v0.1.0 documentation rather than the repository head. Furthermore, deployments connecting to stdio upstreams require distinct process management configurations compared to standard HTTP services to maintain execution lifetime.

What to watch after Byward – put any MCP server behind OAuth 2.1

As organizations integrate Model Context Protocol tooling into development environments, authentication layers like Byward serve as a critical bridge between enterprise identity providers and autonomous software agents. Technology leaders should track future repository updates as Byward advances along its feature backlog toward a stable 1.0 release. Future milestones are expected to address expanded identity provider integrations beyond Microsoft Entra ID, extended access gate rules, and dedicated backup procedures for SQLite volumes. Teams should review architectural decision records and non-goals to plan future infrastructure.

Tracking evolving client specification compliance remains essential as AI desktop tools update their OAuth 2.1 implementations. Developers should watch test results across the official TypeScript, Python, and Go MCP SDKs alongside the MCP Inspector to ensure ongoing interoperability. As Claude Code, ChatGPT, VS Code, and claude.ai standardize on Client ID Metadata Documents, enterprise platform teams can deploy centralized tool gateways with minimal manual client setup. Ongoing community contributions under the Apache-2.0 license will help establish standardized security practices for enterprise MCP architectures.