supercarto (Python)

LLM-native spatial middleware for Python. Give an AI agent a map of any location on earth as a token-budgeted topological graph it can reason over.

pip install supercarto

This package is a client. The map compilation, token budgeting, topology work, and indoor graph live in the Node library, and this speaks MCP to it over stdio. That is deliberate: those algorithms are the product, and a second implementation in a second language would be a second thing to keep correct.

Node 20 or newer is required to call anything. pip install alone will succeed; the error when you call will tell you exactly what to install.

npm install -g supercarto     # or: npx supercarto mcp

Use

import asyncio
from supercarto import SuperCarto

async def main():
    async with SuperCarto() as carto:
        m = await carto.maplet(lat=35.6833, lon=139.7620, radius_m=400, budget=1500)
        print(m.yaml)
        print(f"{m.tokens} tokens, from {m.fetched_from}")

asyncio.run(main())

map:
  center: "35.6833, 139.762"
  radius: 400m
nodes:
  n8: {type: transit, name: 芝浦ふ頭, tags: [station]}
edges:
  n1->n2: {dist: 120m, dir: east, path: road}
omitted:
  - {layer: feature, count: 1754}

The budget holds. The server measures its own output and cuts until it fits, so m.tokens will not exceed m.budget.

Routing

r = await carto.route(37.7749, -122.4194, 37.7849, -122.4194, mode="walk")

r.distance_m, r.duration_s
r.steps  # ["1. head onto Mission St (120m)", ...]
r.source # "osrm", or "straight-line" for the labelled approximation

Weather

No API key needed.

w = await carto.weather(35.6833, 139.7620, hours=12)

w.summary          # "heavy rain"
w.precipitation    # "rain" | "snow" | "sleet" | "hail" | "drizzle"
w.feels_like_c     # what a person actually feels
w.advisory         # prose, in the vocabulary of the decision

Traffic

Needs TOMTOM_API_KEY or HERE_API_KEY in the environment.

t = await carto.traffic(37.7749, -122.4194, 37.7849, -122.4194)

if t.free_flow_only:
    # No credential. The duration ignores congestion entirely. Do not quote it
    # as an arrival time.
    ...

t.worst_level  # the segment that actually makes someone late

traffic() raises ToolError when no credential is configured. That is on purpose: a free-flow number returned as if it were live is the failure this library exists to avoid.

Checking what is available

tools = await carto.tools()

Worth doing before a loop. get_traffic is absent unless a flow credential is present, and get_weather is present by default because its source needs no key. A maplet lists exactly the tools this deployment can answer.

In an agent framework

Any MCP client works; this package is for when you want the typed results.

# LangChain-style MCP config
{
    "mcpServers": {
        "supercarto": {"command": "npx", "args": ["supercarto", "mcp"]}
    }
}

Configuration

Read from the environment by the server, so nothing is needed on the Python side.

SUPERCARTO_PMTILES      PMTiles archive; the production data source
OVERPASS_ENDPOINT       your own Overpass instance
TOMTOM_API_KEY          enables live traffic
HERE_API_KEY            enables live traffic

Point at a specific binary with SUPERCARTO_SERVER_CMD, or pass command=[...] to the constructor. A relative or absolute path both work:

carto = SuperCarto(command=["node", "/opt/sc/dist/cli/main.js", "mcp"])

Errors

They are deliberately distinct. Conflating them would make a retry loop hammer a server that is behaving correctly.

Zero dependencies

This package has no runtime dependencies, on purpose.

The mcp SDK pulls in httpx, pydantic, and their transitive trees. An agent framework that already depends on any of those should not get a second copy at a different version. Three JSON-RPC methods and one line-delimited framing are small enough to implement directly, which is what client.py does.

The trade: pip install supercarto does not bring Node with it. Calling anything raises a SuperCartoConnectionError that says so, with the fix, in one sentence.

Links

• npm: https://www.npmjs.com/package/supercarto
• Repository: https://github.com/Unselfisheologism/supercarto
• Benchmark: https://github.com/Unselfisheologism/supercarto/blob/master/docs/benchmark.md

Apache-2.0