gods-eye-view/docs/TOOLS.md

Tools and the MCP server

Tools answer questions from God's Eye View data for language-model clients. They are defined once and exposed through adapters: the Model Context Protocol (MCP) and function calling, which voice uses.

Layers

Owner	Responsibility
src/tools/	Tool definitions, catalog composition, argument validation, shared area and result helpers
src/tools/queries/	Queries, one file per domain, reading only portable source contracts
src/tools/mcp/	MCP protocol (JSON-RPC) and a stateless HTTP transport; knows the catalog interface, not queries
src/tools/functions.js	Function-calling adapter: tool records and results for function-calling clients
src/tools/services.js	The default services: the layers' source factories and request services, given a resolving fetch
server/mcp/	Node composition: points the sources at a running app's /api routes; serves stdio and /mcp
server/standalone/voiceTools.js, src/standalone/toolCatalog.js	Standalone voice composition: the session's tool list and the browser catalog

Dependencies point downward only. gods-eye-view/tools and gods-eye-view/tools/mcp are portable exports: they reach no application, rendering, Node, Cesium or browser-global code, which npm run check:boundaries enforces. In the application, only voice reaches them: withToolCatalog in src/voice/gevRealtime.js imports the function-calling adapter, and the standalone entry supplies the catalog.

Definitions and composition

defineTool({ name, kind, title, description, inputSchema, requires, run }) validates and freezes a tool. kind is query (answers from data, read-only) or action. inputSchema uses a JSON Schema subset that src/tools/schema.js checks completely; unsupported keywords are rejected at definition time. run(args, { services, signal }) resolves to { summary, data }: one sentence for people and a structured object for programs. A tool may also return images, each { mimeType, data } with base64 data; the MCP adapter sends them as image content. MCP results carry the summary and the data as JSON text, plus the data as structuredContent, for clients that read only one of them.

composeCatalog({ tools, services, replace, interceptors }) builds a catalog:

• Tools: an application adds its own tools to coreTools. Reusing a name fails unless the name is listed in replace.
• Services: each tool names the services it reads in requires. Tools whose services are not supplied are left out.
• Interceptors: (call, next) => next(call) functions wrap every call, outermost first. They can observe, reject or change a call.
• Composite tools: run receives tools, with has(name) and call(name, args), to call other tools through the same catalog, so replaced tools and interceptors apply. Interceptors see such calls with parent, the calling tool's name.

Surfaces

src/tools/surfaces.js lists which tools MCP and voice offer. A tool is on both unless TOOL_SURFACES turns it off; edit an entry to turn a tool on or off for one surface. catalogForSurface(catalog, surface, overrides) is the view a surface exposes: it lists and calls only the tools it offers, while composite tools still reach the whole catalog. toolsForSurface gives the same selection as a list of definitions, such as for the voice session's tool list. Voice leaves out tools that answer with images, link to the app, or repeat what its app actions answer.

Expected failures throw ToolError with one of invalid_arguments, unavailable, unsupported, malformed or retry_later. Other errors are reported to clients without details.

Services

gods-eye-view/tools/services builds the default set with createToolServices({ fetchImpl, appUrl }). Services are the portable source factories the layers already use, such as createUsgsEarthquakeSource, createFirmsSource and createLaunchSource, plus a places service with resolve(name, { signal }). Sources request relative /api/... paths through an injected fetchImpl, so the same tool code runs wherever an application routes those paths. The weather, regional, terrain, summary and features services are the application request services from gods-eye-view/application/requests. situation_brief and military_awareness run each section whose services are supplied and mark the others unavailable. app is { baseUrl }, the address links open. The bikeshare service is { systems, getStations }: the system registry and the GBFS source. createGeocodePlaceService resolves place names through /api/geocode; createPlaceSearchService searches /api/google/* and reports when no search key is configured; createRouteService plans routes through /api/route.

The area argument

Location-scoped tools take area as exactly one of a place name, a bbox ([west, south, east, north], crossing the antimeridian when west exceeds east), or lat, lon and radius_km. Lists default to 25 rows, at most 200, and report total, returned and truncated.

MCP

createMcpServer({ catalog, name, version, instructions, descriptions, decorate }) implements initialize, ping, tools/list and tools/call for protocol revisions 2025-11-25, 2025-06-18 and 2025-03-26. descriptions overrides a tool's title or description for this surface; decorate(definition, tool) merges extra fields into each listed definition. createMcpHttpHandler(server) returns a Request-to-Response handler for stateless Streamable HTTP: one JSON-RPC message per POST, answered with JSON. The host owns routing and any access control in front of it.

Voice

Voice offers the catalog's queries next to its app actions. toFunctionTools(tools, { exclude }) turns tools into { type: 'function', name, description, parameters } records, and toFunctionOutput(name, result) turns a result into { ok, tool, summary, data }, counting images in images_omitted instead of sending them.

The voice session token endpoint takes its tool list as realtime.tools. realtimeSessionTools(additional) appends function tools to the app actions, skipping names an action already uses, so next_satellite_pass stays the action. The standalone server supplies the core queries that src/tools/surfaces.js offers on voice, which leaves out tools that answer with images, link to the app, or repeat what voice's app actions answer (aircraft, ships, earthquakes, fires, datacenters, dams and satellites overhead, which analyst_query covers).

In the browser, initGevVoiceCommands({ toolCatalog }) takes a function that resolves a catalog. App action names go to the action runner; other names the catalog has go to catalog.call with the call's abort signal. The standalone entry composes the catalog with createToolServices over the page's fetch and loads it the first time voice calls a query.

Running locally

Start the app (npm run dev or npm run preview), then register the stdio server with an MCP client, for example Claude Code:

claude mcp add gods-eye-view -- npm --prefix /path/to/gods-eye-view run --silent mcp

npm run mcp -- --api-base http://localhost:4173 selects another server.

The development and preview servers also serve the same tools over HTTP at /mcp, for clients that connect by URL:

claude mcp add --transport http gods-eye-view http://localhost:4173/mcp

The route accepts only requests from this machine that name a loopback host and, when a browser sends an Origin, come from a loopback origin. This is local transport safety, not authentication. The local server makes no requests other than to the app's /api routes and the public feeds the sources already use.

Tools

Tool	Reads	Returns
get_earthquakes	earthquakes	USGS M2.5+ events in the last 24 hours, strongest first
get_active_fires	fires	NASA FIRMS detections in an area, highest radiative power first
get_recent_launches	launches	Launch Library 2 launches in the last 30 days, newest first
aircraft_in_area	aircraft	Aircraft in an area, nearest first; military: true reads the military feed
find_aircraft	aircraft	Aircraft anywhere by callsign, ICAO address or registration
get_aircraft_track	aircraft	Recent positions of one aircraft, thinned to 200 points
get_aircraft_info	aircraft	Aircraft type and registration, and flight route, from adsbdb
vessels_in_area	vessels	Ships reported by AIS in an area, nearest first, optionally by type
find_vessel	vessels	Ships anywhere by MMSI, IMO number or name
get_vessel_track	vessels	Recent positions of one ship, thinned to 200 points
next_satellite_pass	satellites	Next pass over a place or point (default the ISS), with naked-eye visibility
satellites_overhead	satellites	Satellites in a CelesTrak group above a place or point now, highest first
find_cctv_cameras	cctv	Public cameras in an area, nearest first
get_cctv_snapshot	cctv	The current image from one camera, returned as image content
find_alpr_cameras	alpr	OpenStreetMap-mapped license plate readers in a US/Canadian area up to 3°
find_radio_stations	radio	Radio Browser stations by area and/or search terms, with stream URLs
search_places	placeSearch	Points of interest matching a query within an area (Google Places)
places_nearby	placeSearch	Notable places around a place or point (Google Places)
plan_route	routing	Walking, driving or cycling route over OpenStreetMap, with a simplified path
get_bike_share	bikeshare	Live GBFS stations in an area, with bikes and docks available
get_transit_vehicles	transit	Live GTFS-Realtime vehicle positions in an area, optionally one route
get_traffic_flow	traffic	TomTom flow in a city-sized area: speed vs free flow, congested and closed road
get_weather	weather	Current conditions at a place or point
get_weather_map	weatherMaps	The latest NOAA radar, satellite or lightning map image over an area
get_wind	wind	GFS or IFS model wind 10 m above ground at a location
get_recent_imagery	imagery	The most recent clear Landsat/Sentinel-2 image of an area (VIIRS fallback)
find_submarine_cables	cables	TeleGeography cables and landing points by area or name (CC BY-NC-SA 3.0)
find_infrastructure	infrastructure	OpenStreetMap datacenters or dams in an area, nearest first (ODbL)
get_bhote_koshi_flood	events	The 2026 Bhote Koshi flood: evidence trail in story order, flood path and imagery dates (CC BY-NC 4.0)
get_regional_brief	regional	What and where a location is, its weather and recent headlines
get_cyclones	cyclones	Active NHC/CPHC tropical cyclones, optionally in an area
get_fire_perimeters	perimeters	Mapped WFIGS wildfire perimeters in an area, largest first
get_terrain_height	terrain	Ground, geoid and ellipsoid heights at up to 20 points
find_military_installations	installations	OpenStreetMap military sites in an area of at most 10° per side
get_map_features	features	Administrative areas, named places or monuments at a location (needs Overpass)
situation_brief	weather	Weather, earthquakes, fires, aircraft, ships and cyclones for an area, by section
military_awareness	military	Military and other aircraft, ships and military installations within 250 km of a point, by section
get_hud_caption	weather, summary	The app's heads-up display caption for an area
open_in_gods_eye_view	app	A share link looking straight down on an area, with chosen layers on