Arpelier AI connector

What the connector does

MCP (Model Context Protocol) is an open protocol that lets an AI assistant call tools provided by another service. Through the Arpelier connector, an assistant writes a process flow as a Flow 1.0 JSON document, the format the web app reads, and then checks and calculates it. The numbers the tools return are measured from the structure that Arpelier’s engine calculated. The model is geometric, with lengths in nanometres; it is not a fabrication recipe, a detailed physical simulation or an electrical sign-off.

• Read Arpelier agent docs (arpelier_read_docs): returns Arpelier’s published documentation for writing Flows, including the format, process kinds and fields, material IDs, mask polarity and example Flows.
• Validate a Flow (arpelier_validate_flow): checks a Flow with the web app’s own parser and lists each problem with its location in the JSON.
• Compute a Flow (arpelier_compute_flow): calculates the structure up to a chosen step and returns each material’s volume and the height range of the top surface.
• Cross-section of a computed Flow (arpelier_cross_section): returns a section as a character map and, for vertical sections, the layer stack with each layer’s material and boundaries in nanometres.
• 3D picture of a computed Flow (arpelier_render_structure): returns a picture of the calculated 3D structure seen from one corner, in the materials’ colors. Materials can be left out to show what is inside. The cross-section tool can also return its section as a picture.
• Interactive 3D preview (arpelier_preview_structure): in Claude, shows the structure in the conversation with its process timeline to rotate, zoom, step through, expand and open in Arpelier; it is calculated in your browser. Large structures are shown as a picture.
• Sweep process parameters (arpelier_sweep_flow): calculates variants of a Flow over listed values of up to two process fields (up to 16 combinations) and returns a row per variant with the top surface, volumes and, optionally, the section measurements.
• Measure CD, sidewall angle and film coverage (arpelier_measure_section): on a vertical section, measures the widths of materials or openings at chosen heights, sidewall angles, and a film’s thickness on top, bottom and walls with its step coverage.
• Inspect connectivity and contact (arpelier_inspect_structure): checks whether two materials share a contact area and whether points are connected through the materials you name.
• Open a Flow in the Arpelier app (arpelier_open_in_app): makes a link that opens a valid Flow in the web app as a new, unsaved project with every step filled in, and with the calculated result of the last step when it can be included. The link is kept for 7 days. When a 3D file is asked for, the app opens its export menu with that format (GLB, 3MF or STL) chosen; the file is made in your browser.
• Material info for a 3D export (arpelier_export_structure): returns the material information that a 3D export carries. The GLB, 3MF and STL files themselves are made in the web app.

Ten of the eleven tools are marked read-only: they do not create, change or delete anything in Arpelier. The link tool keeps only its link record and does not touch any account or existing project. A call whose steps match an earlier call up to some point continues from the structure kept from it (see Limits); otherwise it calculates the Flow from its first step. The result is the same either way.

Add the connector to Claude

Arpelier is listed in Claude’s Connectors Directory as a Community connector: claude.ai/directory/connectors/arpelier. It uses no sign-in. Before you connect a Community connector, Claude reminds you that Anthropic has screened it but not reviewed it in depth.

1. On an individual plan, open the listing, or find Arpelier under Customize > Connectors in Claude, and add it.
2. In a conversation, open the + menu, choose Connectors and turn on Arpelier.

On a Team or Enterprise plan, an Owner adds Arpelier for the organization under Organization settings > Connectors, and members then connect it under Customize > Connectors. On a Team plan, a member who cannot enable connectors sees Request, which asks the Owners. Claude’s menus can change; Anthropic’s guide to the Connectors Directory has the current steps.

If you added Arpelier earlier by its URL as a custom connector, it keeps working; if Arpelier then appears twice in your connectors, remove one. To add it by URL instead, add a custom connector with the server URL https://arpelier.com/mcp, choose no sign-in, and leave the OAuth fields and request headers empty; Anthropic’s guide to adding a connector by URL has the steps.

In Claude Code, run claude mcp add --transport http arpelier https://arpelier.com/mcp. Other MCP clients that connect to remote servers over Streamable HTTP can use the same URL without authentication.

Example requests

Ask in your own words; the assistant chooses the tools. Each example below uses a different part of the connector.

1. Build and measure. “Using Arpelier, make a flow that deposits 20 nm of oxide on a silicon substrate, opens a 40 nm square window in it with photolithography and an etch, and tell me the measured oxide thickness beside the window and inside it.” The assistant reads the documentation, writes and validates the Flow, calculates it and reads the layer stacks from a cross-section.
2. Find mistakes in a Flow. “Here is my Arpelier Flow JSON. Check it, explain each problem and give me a corrected version.” The assistant runs the validator and explains each issue at its location in the JSON.
3. Check an early step. “Calculate this Flow only up to its first etch step and show me a cross-section through the middle of the mask opening, so I can confirm the mask polarity.” The assistant calculates to that step and returns the section map with its layer boundaries.
4. Check contact. “In this Flow, does the tungsten plug touch the silicide at the bottom of the contact hole, and how large is the shared area?” The assistant runs an interface check between the two materials and reports the measured contact area.
5. Prepare a 3D export. “Which materials would a 3D export of this structure contain, and how much of each?” The assistant returns the export’s material information; the 3D files themselves are exported in the web app.

Put a result into an Arpelier project

The connector has no access to Arpelier accounts or projects, and the web app does not open Flow JSON files. A Flow that an assistant checked with the connector reaches a project in one of these ways.

• A link. Ask the assistant for a link to open the result in Arpelier. It opens a new, unsaved project with every step filled in. When the link carries the calculated result, the app shows it right away; otherwise the app calculates it there. Sign in and save to keep it. The link and the project in it, including names and notes and the calculated result, are kept for 7 days, and anyone with the link can open it until then, so share it only with people who may see the Flow. A changed Flow needs a new link.
• In your open tab. If the assistant can also operate your browser, open a new or empty project in Arpelier and ask it to build the checked Flow there. It uses the web app’s browser API to build the structure step by step in front of you. The agent documentation tells it to work only in an empty or new project and to ask you before replacing existing steps.
• If a link cannot be made, the assistant gives you the final Flow JSON and says that it is not saved. The agent documentation at /llms.txt (written in Korean) describes how a Flow is loaded into a project through the browser API.
• A project is saved only when you save it, or ask the assistant to, while you are signed in. When a project made either way is first saved to an account, Arpelier records how it was made and the name the assistant gave, and shows an AI-generated mark, which the owner can hide in the project’s Share settings.

Limits

• Each calculation can use about 160,000 lateral grid cells, the domain length divided by the grid spacing in x multiplied by the same in y, and up to 400 executed steps after repeated groups are expanded.
• A request can be up to 1 MiB, and one tool call calculates for about 3 minutes (180 seconds). A calculation that needs longer returns IN_PROGRESS with the steps it completed; when the assistant calls the tool again with the same request, the calculation continues where it stopped, so a long calculation finishes over several calls.
• To make that possible, the connector keeps the calculated structure for up to one hour. A later call whose steps match up to some point continues from there: a Flow built module by module calculates only its new steps, and sections or checks of a Flow that was just calculated do not calculate it again. If the progress cannot be kept, a calculation that runs out of time ends with TIME_LIMIT; then check a cropped region or build the full structure in the web app.
• A larger structure can be built in the web app, and a cropped region of it checked with the connector.

The connector calculates geometry. It does not predict electrical characteristics, equipment recipes or fabrication results; see Arpelier vs TCAD for that boundary.

What the connector receives and keeps

When an assistant calls the connector, Arpelier receives the Flow and tool inputs that the assistant sends: process steps, materials, masks, dimensions and any notes in the Flow. It does not receive your name, email address, Arpelier account or the rest of your conversation, and it sets no cookies. The Flow itself is not stored, except in a link you ask for: then the project made from the Flow, including its names and notes, and the calculated result of its last step when included, are kept for 7 days so the link can open it, and anyone with the link can open it until then. To continue long or module-by-module calculations, the calculated structure (the grid of materials, with the IDs and kinds of the steps that made it, but not the Flow, its names or notes) is kept for up to one hour, found only by a fingerprint of the calculation steps and linked to no account or IP address, and is then deleted automatically. As with other requests, the hosting provider’s operational logs record the time, path, status, duration and the caller’s IP address and user agent, and for each tool call its name, result code and duration (not its inputs or results). Leave information you must keep confidential out of a Flow you send.

The full policy is in the Arpelier Privacy Policy under “AI connector requests”. The assistant you use is covered by its provider’s own terms.

Support

For questions, problems or a security report, email contact@arpelier.com. Include the request you made and, where you can, the Flow JSON, leaving out anything confidential.