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Developer ToolsCase study

JarvisMCP

One gateway, two tools, hundreds of capabilities

Built with
TypeScriptNode.jsworkerdV8 IsolatesExpressMCPStreamable HTTPesbuild

Inside the project

01 / 01

JarvisMCP project artwork: many capabilities routed through one gateway.

JarvisMCP1 / 1

JarvisMCP — Code Mode MCP gateway

JarvisMCP project artwork: many capabilities routed through one gateway.

The brief

A problem worth
building around.

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.

Our approach

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.

The experience

What it lets
people do.

The capabilities that turn the underlying engineering into a usable product.

  1. 01

    Find the right capability

    A discovery layer lets an agent look up the tools relevant to a task. It keeps a broad integration surface navigable without putting every tool definition into every interaction.

  2. 02

    Connect actions into a workflow

    Code Mode lets an agent compose calls and use their returned data in the next step. The gateway brings those integrations behind a consistent execution interface.

  3. 03

    Keep the work accountable

    Governed access and durable coordination give ongoing work a place to record ownership, progress and evidence. An agent conversation can hand off its work without becoming the only record of what happened.

Project record

What came out of it.

  • 62 services and 558 discoverable methods reachable through exactly 2 tools

  • Capabilities discovered on demand instead of loading every endpoint into the model context

  • 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

2 tools
Tool surface
62
Services
558
Methods
5 September 2026
Catalogue checked

Under the hood

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
62 services · 558 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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