Top 5 MCP Gateways for Securing Agent Tool Access in 2026

Security firm Knostic scanned the internet for exposed Model Context Protocol servers and found 1,862 of them, and every one of the 119 it sampled returned a full listing of its internal tools to an unauthenticated request, as reported by CSO Online. MCP gateways exist to close that gap: they sit between agents and tool servers and decide which identity may call which tool, with which credential, under what approval. Bifrost, the open-source MCP gateway built in Go by Maxim AI, is the best overall choice for enterprise teams that need that control plane to hold at production scale. This post ranks the five MCP gateways most worth evaluating for securing agent tool access in 2026, and explains which controls reduce the blast radius of a compromised agent.

What an MCP Gateway Does for Agent Tool Access

An MCP gateway is a control plane that sits between AI agents and MCP servers, enforcing authentication, tool-level authorization, credential brokering, and audit logging on every tool call. Without one, each agent holds its own server configuration and long-lived credentials, and no central system records which tool ran on whose behalf.

The security problem is structurally different from API traffic:

• The caller is a model, not a person. Tool selection is driven by model reasoning, so an injected instruction in a document or a tool response can redirect what gets called.
• Tool descriptions are inputs. Metadata that the model reads is attacker-reachable, which is what makes tool poisoning and description rewriting viable.
• Credentials outlive the request. Agents authenticate once and work for long sessions, so authorization must be re-checked at execution time rather than only at connect time.
• Excessive agency is the default. OWASP lists excessive agency among its top LLM application risks, and connecting an agent to every available tool is the fastest way to create it.

Bifrost addresses these as gateway responsibilities: it acts as both an MCP client and MCP server, so agents connect to one governed endpoint rather than to each tool server directly.

What Securing Agent Tool Access Requires in 2026

Score every candidate against the same controls rather than a feature list:

• Tool-level authorization: whether policy restricts individual tools, not just whole servers, and whether the default is deny.
• Identity-scoped credentials: whether each end-user authenticates to the upstream server under their own identity, or every agent shares one admin token.
• Execution control: whether tool calls returned by a model execute automatically or require an explicit approval step.
• Enforcement at execution time: whether authorization is re-checked when the tool runs, not only when the tool list is served.
• Audit trail: whether every call is recorded with identity, tool, and outcome for incident response and compliance.
• Deployment control: whether the gateway runs inside your own infrastructure, since it holds every credential your agents use.
• Context cost: whether the gateway reduces the tool-definition tokens that large MCP footprints push into every request.

The MCP gateway resource page maps these controls to concrete gateway configuration, and the LLM Gateway Buyer's Guide covers the wider evaluation matrix.

Top 5 MCP Gateways for Securing Agent Tool Access

1. Bifrost

Bifrost is a high-performance, open-source AI gateway written in Go that operates as both an MCP client and an MCP server. Agents and clients like Claude Desktop and Cursor connect to a single MCP endpoint, and Bifrost brokers every downstream tool call to connected servers over STDIO, HTTP, or SSE. It adds 11 microseconds of overhead per request at 5,000 requests per second in sustained benchmarks.

Security capabilities for agent tool access:

• Deny-by-default tool filtering: three stacking filter levels (client config, request headers, and virtual key) mean a tool must pass every applicable filter, and a virtual key with no MCP configuration gets no tools at all.
• Per-user authentication: five auth types covering none, static headers, per-user headers, admin OAuth 2.0, and per-user OAuth, so each end-user's credential is stored against their own identity rather than shared across the fleet.
• No implicit execution: tool calls returned by a model are treated as suggestions, and execution requires a separate API call unless Agent Mode is explicitly configured with an auto-execute allowlist.
• Enforcement at execution time: virtual key allowlists are applied at inference and re-applied when the tool executes, and inactive or expired keys are rejected with a 403.
• Tool groups across six dimensions: MCP tool groups attach curated tool bundles to virtual keys, teams, customers, users, providers, or API keys, resolved in-process at request time.
• Context reduction: Code Mode exposes four generic tools instead of hundreds and has the model write sandboxed Python to orchestrate them, cutting input tokens by up to 92.8% in large MCP deployments.

Best for: Bifrost is built for enterprises running mission-critical AI workloads that require best-in-class performance, scalability, and reliability. It serves as a centralized AI gateway to route, govern, and secure all AI traffic across models and environments with ultra low latency. Bifrost unifies LLM gateway, MCP gateway, and Agents gateway capabilities into a single platform. Designed for regulated industries and strict enterprise requirements, it supports air-gapped deployments, VPC isolation, and on-prem infrastructure. It provides full control over data, access, and execution, along with robust security, policy enforcement, and governance capabilities.

2. Docker MCP Gateway

Docker MCP Gateway is an open-source CLI plugin and proxy that runs each MCP server as an isolated container with restricted privileges. Its security model is containment: servers are sandboxed, secrets are injected into the target container at call time instead of living in environment variables, and the gateway can verify image provenance before running a server. Optional flags log every tool call and scan payloads for content that looks like credentials.

The trade-off is scope. Governance stops at the container boundary, so identity-aware policy, per-user credential brokering, and enterprise audit trails need additional systems layered on top. Tool scoping is handled through profiles rather than an identity model.

Best for: teams already standardized on Docker and Compose that want supply-chain and sandbox isolation for locally run MCP servers.

3. IBM ContextForge

ContextForge is an open-source MCP gateway built around federation. It aggregates multiple MCP servers, merges their capabilities, and presents virtual servers so a curated set of tools appears to agents as one logical endpoint. Auto-discovery and health monitoring cover multi-gateway topologies, and it supports JWT bearer tokens, basic auth, and custom header schemes with encrypted credential storage across common relational databases.

The trade-off is operational surface. Federation and composition are strong, but running it means hardening the gateway, its database, and its auth configuration yourself, and it governs MCP traffic only rather than the LLM traffic beside it.

Best for: platform teams that need to compose and federate many MCP servers across environments and are comfortable operating the stack.

4. Kong AI Gateway

Kong extends its API gateway to agentic traffic with MCP-aware plugins and, since early 2026, an MCP Registry in Konnect for cataloging and governing approved MCP servers. Native OAuth 2.1 support lets servers delegate authentication to the gateway while keeping the MCP JSON-RPC contract, tool-level access control lists constrain what agents can call, and Kong's rate limiting and Prometheus metrics extend to MCP endpoints.

The trade-off is that MCP support is layered onto an API management platform. The registry and the richer governance features are tied to the commercial control plane, and the operational model assumes teams already run Kong.

Best for: organizations standardized on Kong for API management that want one policy layer across APIs and MCP servers.

5. Amazon Bedrock AgentCore Gateway

AgentCore Gateway is a managed AWS service that turns REST APIs, OpenAPI specs, Lambda functions, and existing MCP targets into MCP tools behind one endpoint. Identity and audit integrate with IAM, Cognito, and CloudTrail, semantic search over tool definitions helps agents find the right tool in large catalogs, and gateways can target other gateways for aggregation.

The trade-off is portability. It is AWS-only and closed-source with no on-premises option, which rules it out for air-gapped and multi-cloud requirements, and MCP-specific threats such as tool poisoning are outside its security model.

Best for: AWS-native teams whose agents and tools already live inside one account boundary.

MCP Gateway Security Capabilities Compared

Most gateways in this category govern the connection. Fewer govern the execution, and that distinction determines whether a compromised agent can act or only ask. The Bifrost MCP gateway puts both the tool list and the tool call through policy, covered in more depth on the MCP gateway page.

How Bifrost Secures Agent Tool Access

Bifrost treats tool exposure, credentials, and execution as three separate decisions.

Tool exposure is scoped to identity

Virtual keys are the governance entity. A key with no MCP configuration receives no tools, and a configured key produces a strict allowlist enforced when the tool list is generated and again when a tool executes. Enterprise deployments add reusable tool groups that resolve against the virtual key, team, customer, user, provider, or API key on the request, so a support agent and a data engineering agent can share infrastructure while seeing different tools.

Credentials stay attached to the caller

MCP servers rarely need a shared admin token. With per-user OAuth and per-user headers, each end-user authenticates once against services like GitHub or Notion, and the gateway stores that credential against their identity and reuses it on later calls, with token refresh and PKCE handled at the gateway. Enterprise teams can also turn existing internal APIs into governed MCP tools with federated auth instead of writing wrapper servers.

Execution requires an explicit decision

Bifrost does not execute tool calls implicitly. An application reviews the model's proposed calls and invokes the execution endpoint for the ones it approves, which is where human approval belongs for destructive operations. Teams that want autonomy opt into it per tool. Around that, guardrails screen traffic for secrets and unsafe content, audit logs provide immutable trails for SOC 2, GDPR, HIPAA, and ISO 27001, and Bifrost Enterprise supports in-VPC and air-gapped deployment so credentials never leave your network.

Questions Teams Ask About MCP Gateway Security

Does an MCP gateway stop prompt injection?

No gateway removes prompt injection, because tool output reaches the model by design. A gateway limits the consequences: deny-by-default tool exposure narrows what an injected instruction can reach, approval gates keep destructive calls from running unattended, and guardrails screen content in the request path.

What does the MCP specification cover on its own?

The protocol defines an authorization framework for HTTP transports based on OAuth 2.1, but it specifies how a server may authenticate a client, not which tools a given identity should see or whether a call should execute. Those remain gateway responsibilities.

How do MCP gateways affect token costs?

Every connected server pushes its tool definitions into context on each request, and large footprints dominate the prompt. Code Mode exposes four generic tools and has the model orchestrate the rest in a sandbox, which cut input tokens by up to 92.8% in benchmarked deployments of 16 servers and 508 tools.

Can one gateway govern both LLM and MCP traffic?

Yes, and separating them duplicates policy. Bifrost applies the same virtual keys, budgets, rate limits, and audit trail to model calls and tool calls, so access control does not fragment across two systems.

Getting Started with Bifrost as an MCP Gateway

Among the MCP gateways built for securing agent tool access, Bifrost is the only option that combines deny-by-default tool filtering, per-user credential brokering, explicit execution control, unified LLM and MCP governance, and an open-source core under Apache 2.0 at 11 microseconds of overhead. Teams can point Claude Desktop, Cursor, or a custom agent at one governed endpoint and scope tools per identity from the first day.

To see how Bifrost governs agent tool access across your MCP servers, book a Bifrost demo with the team.