Centering Lab

Measure card centering and check PSA, BGS, CGC and SGC centering ceilings and standards.

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What it can do

    What data it sees

    Do you need an account

    No: the server works without sign-in

    Measure card centering and check PSA, BGS, CGC and SGC centering ceilings and standards.

    How to connect

    How to connect Centering Lab to Claude

    The server address to paste into Claude settings:

    https://centeringlab.com/mcp

    1. Open Claude (claude.ai or the desktop app).
    2. Go to Settings → Connectors.
    3. Click Add custom connector.
    4. Paste the server address copied below into Remote MCP server URL and click Add.
    5. In a chat, click + → Connectors and switch the new connector on.

    Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

    Authorization

    After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

    How to connect Centering Lab to ChatGPT

    The server address to paste into ChatGPT settings:

    https://centeringlab.com/mcp

    1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
    2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
    3. Open Settings → Connectors and click Create.
    4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
    5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
    6. In a new chat open + → Apps/Connectors and enable the connector.

    OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

    Authorization

    On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

    How to connect Centering Lab to Cursor

    The server address to paste into Cursor settings:

    https://centeringlab.com/mcp

    Fastest: click Open in Cursor below and confirm the prompt.

    Manually:

    1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
    2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
    3. Save the file. The server appears in the MCP list; authorize it there if asked.

    Authorization

    If the service needs sign-in, an authorize button appears next to the server in the MCP list.

    Server tool list (3)

    Raw names from tools/list. Only developers need these.

    grade_centeringUSE THIS TOOL whenever the user supplies numeric centering ratios and asks whether a card meets PSA/BGS/CGC/SGC or asks for a centering ceiling. Do not calculate by looking up standards yourself. Example: {"front_lr":"55/45","front_tb":"60/40","house":"PSA"}. At least one known face AND axis; if either is unknown, ask first, never assume front/LR. Optional house PSA/BGS/CGC/SGC, TAG excluded. Flat front_lr/front_tb/back_lr/back_tb, or nested {"front":{"lr":"55/45","tb":"60/40"}}; no duplicates. Key/house case accepted. Ratios: percentages, fractions, pairs with / - – — : x or spaces, optional %, or [55,45]/["55","45"]. Scalar 1 rejected; use 1/99. Axis suffix must match field. Changes disclosed in normalizations. Partial input gives incomplete=true: report provisional ceiling and missing data. A ceiling from centering alone is NOT a predicted grade. SGC back alone has no published ceiling.
    get_centering_standardsUSE ONLY for questions about published THRESHOLDS, tolerance, rules or SOURCES without grading the user's supplied numeric ratios. For PSA 10 compatibility with supplied ratios use grade_centering instead; it applies rounding and house-specific rules. If face/axis is unknown, ask first without any call. Example: {"house":"BGS","face":"back"}; fields optional, {} returns all. Houses PSA/BGS/CGC/SGC (case accepted), TAG excluded: explain proprietary assessment; never substitute another house. Face front/back in English; case/spaces accepted, reverse/obverse and translations rejected. SGC back has empty bands, no published table or ceiling; never invent one. Returns official/interpreted/approximate status, sources and verification. Not a final-grade prediction.
    measure_card_centeringMeasure one ACTUAL photograph. Example shape: {"face":"front","image_base64":"<complete actual image bytes>"}. Ask front/back BEFORE calling if unknown. Exactly one user-provided public HTTPS image URL (port 443) or complete base64 source, never both. Never decode, repair or re-encode bytes yourself; never invent, shorten or rewrite base64; pass it verbatim, including an image data-URL prefix or whitespace (service normalizes). If chat attachment cannot be forwarded, send user to https://centeringlab.com/. card_size standard=63×88 mm including Japanese Pokémon; small=59×86 mm including Yu-Gi-Oh!, not inferred from language. Request a whole card flat from above on dark surface; if sleeved/toploader or tilted, recommend a retake first. Borderless: suggest back/manual site. API photos reach server memory; site stays local. needs-review/failed gives ceilings=null: retake or adjust manually, no grade prediction. Inspect status/code even on HTTP 200; respect Retry-After.