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WebMCP tools for browser agents

WebMCP is a browser API that lets a web page hand tools to an AI agent running in the browser. The agent calls a tool with arguments and reads a structured answer, instead of reading the page and clicking through it. Every page of terra-lab.ai registers its tools through document.modelContext.registerTool, so an agent on the site can convert coordinates, read a page or call the Data API in one step.

You do not need to install anything. When a browser has no WebMCP support, the site behaves as before and nothing is loaded.

For an agent outside the browser (Claude, ChatGPT, Cursor, a script), connect the MCP server or call the REST API instead.

Tool	What it does
`list_terralab_products`	The QGIS plugins and services, with a one-line description and page for each.
`get_terralab_pricing`	Free tiers and paid plans of the plugins, with the pricing page as the source.
`get_qgis_plugin_install_links`	The plugin marketplace links and the install steps inside QGIS.
`list_free_gis_tools`	The free tools of the site, with what each one does and its page.
`read_terralab_page`	Any page of the site as markdown: product pages, docs, blog posts.
`open_terralab_page`	Opens a page of the site in the tab the agent works in.
`get_terralab_mcp_connection`	How to connect the MCP server and the REST API: URL, sign-in, OpenAPI document.

Free tools, no account

These run in your browser or on the free public endpoints of the site. Nothing is counted.

Tool	What it does
`convert_coordinates`	Converts points between decimal degrees, degrees minutes seconds, UTM, MGRS, Lambert 93 and other EPSG systems, with the input format detected.
`list_coordinate_systems`	Lists the systems `convert_coordinates` accepts, filtered by a word such as Lambert or UTM.
`convert_vector_data`	Converts KML, CSV, GeoJSON, GPX or WKT text into another of these formats; Shapefile, KMZ and Excel outputs are saved as a download.
`build_ogr2ogr_command`	Writes the GDAL `ogr2ogr` command for a conversion, a reprojection or a clip, for bash, PowerShell or cmd.
`get_building_heights`	Height, floors and use of the buildings in a small area in France, from IGN BD TOPO.
`get_building_footprints`	Building outlines in an area from Overture, OpenStreetMap, Microsoft and Google, with counts per source.

Data API tools, on your account

When you are signed in to terra-lab.ai, the agent also gets the tools of the TerraLab Data API: the same tools as the MCP server, such as find_places, get_elevation, get_satellite_image, french_parcel, get_natural_risks and get_route. The list is read from the server's live catalog, so a new tool shows up without a site change. Each tool is described in the API reference.

Calls go through the site with your session and count against your own account, like a call from any agent: free calls first, then your balance. They appear under connected apps on your Data API page as "Browser agent on terra-lab.ai". You accept the Data API terms once on that page before the first call; the agent cannot accept them for you. request_data files a data request with TerraLab, so it is not marked read-only. get_satellite_image, get_satellite_index, extract_open_data and extract_dataset can cost more than one call and ask the agent to confirm first. To turn browser agents off, revoke "Browser agent on terra-lab.ai" on that page: it stays off until you sign in again. See Pricing and limits. Signed out, these tools answer with the sign-in link instead of running.

Your account, read only

Tool	What it does
`get_my_terralab_account`	Your plugin plans and your Data API balance, when you are signed in.

No tool changes your account: none buys, subscribes, creates a key or deletes anything.

Security

Tools are only visible to agents working on terra-lab.ai. Other sites and embedded frames cannot see or call them.
Tools that only read are marked readOnlyHint. The free tools return a link (open_in_browser or edit_in_builder) that opens the same result in the visible tool, and open_terralab_page shows it to you, so you can check what the agent did. Account and payment pages are never opened by a tool. Tools whose answer carries third-party text (open data, file contents) are marked untrustedContentHint, so the agent treats it as data, not instructions.
Data API calls use your existing session. No key or token is handed to the agent.
We record which tool was called, whether it worked and how long it took, never the arguments.

Try it

WebMCP is experimental in Chrome: an origin trial from Chrome 149 to 156, with shipping planned after that.

In Chrome, open chrome://flags/#enable-webmcp-testing, set it to Enabled and relaunch.
Open any page of terra-lab.ai, then DevTools, Application, WebMCP. The panel lists the registered tools, lets you run one with your own arguments, and logs every call an agent makes.
Ask an agent that supports WebMCP in your browser to use the site, for example to convert a list of coordinates or to read the pricing.

Updated 2026-10-28