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Developer ToolsCase study

JarvisMCP

One gateway, two tools, hundreds of capabilities

Project Focus
TypeScriptNode.jsworkerdV8 IsolatesExpressMCPStreamable HTTPesbuild
JarvisMCP — Code Mode MCP gateway

Two tools in front of 57 services, with a hard credential boundary behind them.

2 tools
Tool surface
57
Services
454
Methods
99%+ vs tool-per-endpoint
Token reduction
01

Challenge

The standard way to give an AI agent capabilities is one tool per endpoint. That approach collapses at scale: every tool definition is spent from the context window before the agent has done anything, so a few dozen integrations can consume thousands of tokens purely describing what is available. Worse, each new server is another process to run, another credential to distribute, and another place for a secret to leak into a model's reasoning trace.

02

Solution

JarvisMCP inverts the model. Instead of exposing N tools, it exposes two — one to search a ranked capability catalogue, one to execute code — and lets the agent write JavaScript against a single unified SDK. That code runs inside a workerd V8 isolate under a hard timeout, so arbitrary agent-authored programs are contained by construction. The security property that matters is the boundary: upstream credentials for every integrated system live only in trusted processes on the far side of a loopback line, and nothing the agent writes can reach across it. The isolate can ask for work to be done; it can never see the key that does it.

03

Results

  • 57 services and 454 discoverable methods reachable through exactly 2 tools
  • Over 99% token reduction versus a conventional tool-per-endpoint server
  • Arbitrary agent-written JavaScript contained in a V8 isolate under a hard timeout
  • No upstream credential ever crosses into the sandbox — secrets stay in trusted processes
  • Batching many calls into one execution turns per-call round-trips into a single request
  • Deployed on Docker Swarm with bearer-token auth and per-key rate limiting

System Architecture

Two tools in front of a sandboxed isolate; every upstream credential stays in trusted processes the sandbox cannot reach.

backend
database
service
external
HTTPS + bearersearchexecutejarvis.*no credential crosses hereAuthenticated callsRead / capture
AI Agent
Writes JavaScript, not tool calls
Gateway
Streamable HTTP + bearer auth
Capability Search
Ranked spec lookup, no network
workerd Isolate
Sandboxed V8, hard timeout
Unified SDK
57 services · 454 methods
Trusted Processes
Credential boundary
Connected Apps
Manifest-driven capabilities
Shared Memory
Cross-session context

Two tools in front of a sandboxed isolate; every upstream credential stays in trusted processes the sandbox cannot reach.

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