Toolkit MCP Server

Public Hosted Server: https://toolkit.caseyjhand.com/mcp

Overview

Everyday developer utilities: generate IDs, QR codes, and hashes, encode and decode values, and geolocate a public IP or hostname. Everything but the geolocation lookup runs locally.

Tools

Capability reference

toolkit_hash_value tool

• value read per inputEncoding (utf8 default, hex, base64); algorithm is sha256 (default), sha384, or sha512, with sha1 and md5 for checksum compatibility only; operation is generate or compare, and when omitted it compares if expected is sent
• generate returns digest in digestEncoding (hex default, base64, or sri for the SHA-2 algorithms) plus lengthInBytes; compare returns matches against expected, given as hex, base64, or SRI, including a multi-entry npm integrity value
• A bad expected fails as expected_malformed, expected_length_mismatch (the hint names the algorithm that length fits), or expected_algorithm_mismatch

toolkit_generate_id tool

• type is uuid_v4 (default), uuid_v7, or ulid; count is 1–1000 (default 1)
• ids always holds exactly count values; uuid_v7 and ulid batches are strictly increasing even within one millisecond, with random gaps so no id is derivable from another

toolkit_generate_qr tool

• data up to 2953 UTF-8 bytes at errorCorrection L, less at M (default), Q, and H; format is svg (default), png_base64, or terminal; margin 0–20 modules (default 4), scale 1–32 px per module (default 4)
• Returns content, the symbol version (1–40), mimeType for image formats, and byteLength for PNG; png_base64 also arrives as an MCP image block, and terminal is plain Unicode half-blocks drawn for a dark background
• Over-capacity input fails as data_too_large with its byte count; a PNG over 2048 px per side fails as raster_too_large with a scale that fits, while svg and terminal have no pixel cap

toolkit_encode_value tool

• operation (encode or decode) and encoding (base64, base64url, hex, url) are required; whitespace in hex, base64, and base64url input is ignored, so wrapped MIME and PEM bodies decode as-is
• Decode returns result as utf8 text unless outputEncoding asks for hex or base64, which returns the bytes losslessly and transcodes between encodings; malformed input fails as decode_failed, and binary bytes as decode_not_utf8 rather than with replacement characters

toolkit_geolocate_ip tool

• target is an IPv4/IPv6 address or a dotted hostname, DNS-resolved first; private or reserved addresses fail as private_target, unresolvable hostnames as unresolvable_host
• Or send targets (up to 1000) instead, never both: the first 100 return ordered results with per-target errors, failedCount counts failures, and unprocessedTargets lists the rest to resubmit
• Returns country, countryCode, region, city, latitude/longitude, asn, org, and timezone with resolvedIp and source; a true in proxy, hosting, or mobile means the location describes infrastructure, not a person
• Uses the keyless ip-api free tier over plaintext HTTP by default (TOOLKIT_GEO_BASE_URL, TOOLKIT_GEO_API_KEY); results are cached per resolved IP
• Single and batch lookups have separate rate limits (TOOLKIT_GEO_RATE_LIMIT_PER_MIN=45, TOOLKIT_GEO_BATCH_RATE_LIMIT_PER_MIN=15); refusals report rate_limited with seconds to wait, and cache hits stay free

toolkit_check_network tool

• mode is ping, traceroute, connectivity, or public_ip; target is required except for public_ip, and port (1–65535) for connectivity; count 1–10 pings (default 3), timeoutMs 100–30000 (default 3000)
• A silent host is reachable: false, not an error; ping adds rttMs, sent, received, and packetLossPercent, connectivity adds outcome (open, refused, timeout, unreachable), and traceroute returns hops; an unresolvable host or a ping/traceroute binary that can't run fails as unreachable
• Registered only when TOOLKIT_ENABLE_NET_DIAGNOSTICS=true; private and reserved targets fail as private_target_blocked unless TOOLKIT_ALLOW_PRIVATE_NETWORK=true

toolkit_check_system tool

• what is os, cpu, memory, load, or interfaces; exactly one matching facet object is populated
• memory.availableBytes is the allocation headroom and limitBytes appears under a container memory limit; totalBytes, freeBytes, and usedBytes are raw OS figures that count reclaimable cache as used
• Registered only when TOOLKIT_ENABLE_SYSTEM_INFO=true, since os and interfaces disclose host topology and version details

Features

Built on @cyanheads/mcp-ts-core: stdio and Streamable HTTP transports, pluggable auth (none / jwt / oauth), swappable storage (in-memory, filesystem, Supabase, Cloudflare KV/R2/D1), structured logging with optional OpenTelemetry tracing.

Toolkit-specific:

• Hashing, ID minting, QR encoding, and encode/decode run in-process on node:crypto and the qrcode library, with no upstream calls
• Geolocation calls the provider, never the target, and checks the DNS-resolved IP against private ranges, so a hostname can't reach an internal address
• Fail-closed gating: toolkit_check_network and toolkit_check_system are absent from tools/list unless enabled. Both report on the server's host, not the caller's, so they belong on local or self-hosted deployments
• Two-tier network gate: with diagnostics on, private, loopback, link-local, and reserved targets (the cloud-metadata endpoint included) stay blocked until TOOLKIT_ALLOW_PRIVATE_NETWORK=true

Agent-friendly output:

• Provenance: geolocation echoes resolvedIp and source, and omits fields the provider didn't report instead of inventing them
• Response shaping: provider strings are capped at 256 characters and stripped of control characters, so registry-controlled text like org can't flood or format a model's context
• Discriminated outputs: operation, format, mode, and what echo what ran, and only that branch's fields are populated
• Typed failures: every declared failure carries a reason and a recovery hint, and conflicting inputs (expected with generate, outputEncoding with encode) are rejected by name, not ignored

Getting started

Public Hosted Instance

A public instance is available at https://toolkit.caseyjhand.com/mcp — no installation required. Point any MCP client at it via Streamable HTTP:

{
  "mcpServers": {
    "toolkit-mcp-server": {
      "type": "streamable-http",
      "url": "https://toolkit.caseyjhand.com/mcp"
    }
  }
}

Self-Hosted / Local

Add the following to your MCP client configuration file. No API key is required.

{
  "mcpServers": {
    "toolkit-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["@cyanheads/toolkit-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with npx (no Bun required):

{
  "mcpServers": {
    "toolkit-mcp-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@cyanheads/toolkit-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "toolkit-mcp-server": {
      "type": "stdio",
      "command": "docker",
      "args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/toolkit-mcp-server:latest"]
    }
  }
}

To enable the gated host-probing tools, add their flags to env (or -e for Docker):

"env": {
  "MCP_TRANSPORT_TYPE": "stdio",
  "TOOLKIT_ENABLE_NET_DIAGNOSTICS": "true",
  "TOOLKIT_ENABLE_SYSTEM_INFO": "true"
}

For Streamable HTTP, set the transport and start the server:

MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp

Prerequisites

• Bun v1.4.0 or higher (or Node.js v24+).
• No API key needed — geolocation uses the keyless ip-api free tier by default.

Installation

1. Clone the repository:

git clone https://github.com/cyanheads/toolkit-mcp-server.git

1. Navigate into the directory:

cd toolkit-mcp-server

1. Install dependencies:

bun install

Configuration

All variables are optional.

See .env.example for the full list of optional overrides.

Running the server

Local development

• Build and run:

  # One-time build
  bun run rebuild
  
  # Run the built server
  bun run start:stdio
  # or
  bun run start:http
  

• Run checks and tests:

  bun run devcheck   # Lint, format, typecheck, security, changelog sync
  bun run test       # Vitest test suite
  bun run lint:mcp   # Validate MCP definitions against spec
  

Docker

docker build -t toolkit-mcp-server .
docker run --rm -p 3010:3010 toolkit-mcp-server

The Dockerfile defaults to HTTP transport, stateless session mode, and logs to /var/log/toolkit-mcp-server. OpenTelemetry peer dependencies are installed by default — build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

Development guide

See CLAUDE.md / AGENTS.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic
• Use ctx.log for request-scoped logging, ctx.state for tenant-scoped storage
• Register new tools in the createApp() arrays in src/index.ts; a host-probing tool registers only behind an enable flag
• Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

Contributing

Issues are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

License

Apache-2.0 — see LICENSE for details.