Best Portkey Alternative for MCP Tool Calling in 2026

The Model Context Protocol (MCP) is rapidly becoming the standard for connecting AI models to external tools, data sources, and APIs. As enterprises adopt agentic AI architectures, having an AI gateway that natively supports MCP tool calling isn't optional, it's foundational.

Many teams are discovering that their current AI gateway wasn't designed with MCP in mind. Bolted-on MCP support leads to brittle integrations, high latency on tool calls, and limited observability into agent-tool interactions. If you're looking for a purpose-built alternative that treats MCP as a first-class citizen, Bifrost by Maxim AI is the strongest choice in 2026.

Why MCP Tool Calling Needs a Dedicated Gateway

MCP tool calling introduces unique challenges that generic API gateways weren't built to handle. When an AI agent invokes external tools (databases, APIs, file systems, web search) through MCP, the gateway needs to manage:

• Multi-step tool call orchestration where a single user request triggers chains of sequential or parallel tool invocations
• Low-latency routing because every millisecond of gateway overhead multiplies across tool call chains
• Security-first tool execution ensuring tools are never automatically invoked without explicit approval
• Granular observability into which tools are called, how long each takes, and where failures occur
• Per-consumer tool access controls governing which models, users, or applications can invoke which tools
• Token efficiency since tool schemas loaded into context windows consume significant tokens at scale

Traditional AI gateways handle basic request-response proxying well, but MCP tool calling demands a gateway that understands the full lifecycle of agentic interactions.

Why Bifrost by Maxim AI Is the Best Choice

Bifrost is an open-source, high-performance enterprise AI gateway built in Go, engineered for production-grade AI workloads, including a dedicated MCP Gateway for tool calling.

Here's why Bifrost leads the pack for MCP-powered agentic AI:

Dual-Role MCP Architecture: Client and Server

Bifrost doesn't just connect to MCP servers, it acts as both an MCP client and an MCP server through a single deployment:

• As an MCP client, Bifrost connects to your external MCP servers (filesystem tools, web search, databases, custom APIs) and discovers their capabilities automatically
• As an MCP server, Bifrost exposes all connected tools through a single gateway URL, MCP clients like Claude Desktop connect to Bifrost and access everything in one place
• Supports three connection protocols: STDIO (for local tools and scripts), HTTP, and SSE (Server-Sent Events) for maximum compatibility
• Automatic health monitoring with periodic checks every 10 seconds, using lightweight ping or listTools-based probes
• Add, remove, reconnect, or edit MCP clients at runtime via API, no restarts required

Security-First Tool Execution

This is a critical differentiator. Bifrost never automatically executes tool calls. The architecture is stateless with explicit execution:

• Chat completions return tool call suggestions only, they are not executed
• A separate /v1/mcp/tool/execute API endpoint handles explicit tool execution after your application reviews and approves each call
• Your application maintains full control: validate parameters, check rate limits, apply content filtering, and approve or reject based on business logic
• Agent Mode is available for trusted operations, configurable auto-approval for specific tools via tools_to_auto_execute, so you can selectively enable autonomous execution while keeping sensitive tools gated

Code Mode: 50% Token Reduction for Multi-Tool Workflows

Standard MCP tool calling hits a bottleneck at scale: tool bloat. Each MCP server exposes tool schemas that must be loaded into the LLM's context window. Bifrost's Code Mode solves this:

• Instead of loading hundreds of tool definitions, Code Mode exposes four meta-tools, the LLM writes TypeScript to orchestrate tools programmatically
• 50%+ reduction in token usage and 40-50% reduction in execution latency when working with multiple MCP servers
• 97% reduction in schema overhead and 75% fewer round trips compared to standard tool calling
• Ideal when your agents use 3+ MCP servers where traditional tool schema injection becomes unsustainable

Ultra-Low Latency: <100µs Overhead at 5,000 RPS

• Built in Go for high concurrency and production-grade performance
• Only ~11µs of gateway overhead per request in sustained 5,000 RPS benchmarks, 50x faster than LiteLLM
• In agentic workflows where a single query might trigger 5-10 tool calls, gateway latency compounds fast, Bifrost keeps this negligible
• Zero-config startup: get running in 30 seconds with npx -y @maximhq/bifrost or Docker

Virtual Keys: Granular Tool Access Governance

Bifrost's Virtual Keys are the primary governance entity, and they extend directly to MCP tool access:

• Create different virtual keys for different use cases with independent budgets, rate limits, and tool access policies
• Per-key MCP tool filtering, restrict exactly which MCP clients and tools each virtual key can access using mcp_configs
• Set different tool policies for development, staging, and production environments
• Hierarchical cost control with budgets at virtual key, team, and customer levels
• Supports standard auth headers: Authorization (OpenAI-style), x-api-key (Anthropic-style), and x-goog-api-key (Google-style)

8+ Providers and 1,000+ Models Through a Unified API

• Route across 8+ providers, OpenAI, Anthropic, AWS Bedrock, Google Vertex, Azure, Cerebras, Cohere, Mistral, Groq, Ollama, and more, through a single OpenAI-compatible API
• Drop-in replacement: swap to Bifrost by changing just the base URL in your existing OpenAI, Anthropic, Google GenAI, LangChain, or LiteLLM SDK code
• Automatic failover between providers ensures 99.99% uptime, if a primary provider fails, Bifrost switches to backups automatically
• Intelligent load balancing with weighted distribution across multiple API keys and providers

Native Observability and Monitoring

• Native Prometheus metrics built-in, scrape directly, no wrappers or sidecars needed
• OpenTelemetry (OTLP) integration for distributed tracing with Grafana, New Relic, Honeycomb, and more
• Built-in dashboard via the Web UI for real-time request logs, metrics, and analytics without complex setup
• Track success rates by provider, daily cost estimates, and cache hit rates through pre-built Prometheus queries
• Integration with the Maxim AI observability platform for end-to-end AI evaluation and monitoring

Open Source and Self-Hostable

• Fully open source on GitHub under Apache 2.0
• Self-host anywhere, your cloud, your data center, Docker, Kubernetes, or bare metal
• Web UI, API-driven, or file-based configuration, choose what fits your workflow
• Active Discord community with responsive support and regular updates
• Enterprise tier available with additional features: guardrails (AWS Bedrock, Azure Content Safety, Patronus AI), clustering, adaptive load balancing, MCP with Federated Auth, vault support, and audit logs

Traditional Gateways vs. Bifrost for MCP Tool Calling

Getting Started with MCP Tool Calling on Bifrost

Setting up Bifrost as your MCP gateway is straightforward:

• Install Bifrost with a single command: npx -y @maximhq/bifrost or docker run -p 8080:8080 maximhq/bifrost
• Open the Web UI at http://localhost:8080, configure providers and MCP connections visually with zero config files
• Connect MCP servers via the API, define STDIO, HTTP, or SSE connections and specify which tools to expose
• Create virtual keys with MCP tool filtering to control which consumers can access which tools
• Choose your execution model, use explicit tool execution for safety-critical workflows, or enable Agent Mode for trusted autonomous operations
• Point your existing SDK at Bifrost, change one line (the base URL) and all tool calls route through the gateway automatically

Explore the full MCP Gateway documentation for detailed setup guides.

Who Should Switch to Bifrost for MCP Tool Calling?

Bifrost is the right fit if:

• You're building agentic AI applications where models interact with external tools and APIs through MCP
• You need security-first tool execution where no tool runs without explicit approval (unless you opt into Agent Mode)
• Your agents use multiple MCP servers and you need Code Mode to reduce token bloat and round trips
• You require per-consumer tool governance with virtual keys, budgets, and granular tool filtering
• You want a single gateway URL that exposes your entire tool ecosystem to Claude Desktop and other MCP clients
• Compliance and security demand audit trails, guardrails, and fine-grained access controls

Final Verdict

MCP tool calling is transforming how AI applications interact with the world, but it demands an AI gateway architected specifically for the complexity of agentic workflows. Generic gateways that treat tool calls as just another API request leave critical gaps in security, token efficiency, governance, and observability.

Bifrost by Maxim AI is purpose-built for this: an open-source AI gateway built in Go with a dedicated MCP Gateway that acts as both client and server, security-first tool execution, Code Mode for 50%+ token savings, virtual key governance with per-tool filtering, and ~11µs gateway overhead at scale.

Ready to power your agentic AI with production-grade MCP tool calling? Get started with Bifrost →