Experts in AI apps

Use your Chat.co experts in ChatGPT

Add Chat.co as a custom connection in ChatGPT developer mode while the directory listing is in review.

8 min readUpdated September 2026

Key takeaways

  • The ChatGPT directory listing is in review and not yet published.
  • You can connect today in developer mode on the web, where your plan and workspace allow it.
  • Authentication is OAuth: you sign in to Chat.co and choose one workspace.
  • ChatGPT may ask you to confirm each expert question, because it saves a conversation and uses credits.

1. Availability

ChatGPT

In vendor review

Directory submission in review

The public ChatGPT listing is not published yet. You can connect today as a custom connection in developer mode, where your plan allows it.

Server URL
https://mcp.chat.co/mcp
Permission
chatco:read
Status reviewed
30 September 2026

Chat.co has been submitted to OpenAI for the ChatGPT directory and is in review. Until OpenAI publishes it, Chat.co does not appear when you browse ChatGPT's directory.

The developer-mode connection below works now. We tested it end to end: listing experts, a cited answer, a follow-up, a direct search and opening a source.

2. Before you start

  • Your own Chat.co account. You sign in yourself during setup. Never use another person's login.
  • A workspace with at least one expert you can chat with in Chat.co, on an active plan. If someone else manages the account, they give you access to experts; see Team, roles & seats.
  • Message credits in that workspace for expert answers and standalone searches. Listing experts and opening sources are free.
  • Optional: permission to search an expert's knowledge directly. You only need it for standalone search. Asking questions and opening an answer's citations do not require it.
  • ChatGPT on the web with developer mode. OpenAI lists developer mode for Plus, Pro, Business, Enterprise and Education accounts on the web. Availability can also depend on your workspace's policy, so a workspace admin may need to allow it.

3. Add Chat.co in developer mode

  1. 1

    Turn on developer mode

    In ChatGPT, open Settings → Security and login and switch on Developer mode. OpenAI marks developer mode as elevated risk. Only add servers you trust.

  2. 2

    Create a connection

    Go to chatgpt.com/plugins and select the + button. Enter a name, such as Chat.co, and a short description, such as “Ask my Chat.co experts for cited answers.”

  3. 3

    Enter the server URL

    Under Connection, choose the public endpoint and enter the URL, including /mcp:

    url
    https://mcp.chat.co/mcp
  4. 4

    Choose OAuth

    Set authentication to OAuth. If ChatGPT shows advanced OAuth settings, use the values below. Leave client ID and secret fields empty; Chat.co never needs an API key here.

    SettingValue
    Client registrationDynamic client registration
    Scopechatco:read
    OpenID Connect (OIDC)Off
  5. 5

    Create and sign in

    Create the connection. ChatGPT opens the Chat.co sign-in page; approve it as described in Approve in Chat.co. Back in ChatGPT, review the discovered tools: list_authorized_experts, consult_expert, search and fetch.

  6. 6

    Use it in a conversation

    Start a new conversation, open the + menu, choose Developer mode and select Chat.co.

4. Approve in Chat.co

Every host sends you to the same Chat.co approval page. Sign in if asked, then check each part before you approve:

On the approval pageWhat it means
Signed in asThe Chat.co account the app will act for. If it is the wrong account, cancel, sign out of Chat.co and start again from the app.
Workspace and billing accountThe one workspace this connection uses. Its experts, permissions and message credits apply. To use a different workspace later, disconnect and connect again.
This application will be able toAsk your experts and receive answers, citations and supporting-document links. Search knowledge you are permitted to read and open the sources it returns. When you ask for one, an expert may also produce an assessment or other file, which the app receives as a download.
CannotManage or delete your chatbots. The connector has no tools for editing knowledge, settings, team members or billing.
Connection detailsThe requesting app’s client ID and return address. Use them to confirm this is the app you started from.

Choose Approve connection to finish, or Cancel to stop. The only permission requested is chatco:read. It means the app cannot change your chatbots, knowledge, settings or account. It does not make the connection free of side effects: asking an expert saves the conversation in Chat.co and uses message credits, and a standalone search uses credits too, exactly as in the Chat.co app. Your questions, and the answers, excerpts and files you are permitted to receive, pass to the AI app and its provider.

5. Your first cited answer

Run these in a new ChatGPT conversation with Chat.co selected. HR Handbook is a made-up example; use the name of one of your own experts.

  1. 1

    Discover your experts

    prompt
    Which Chat.co experts can I ask?

    Expect: the experts in the workspace you approved, with short descriptions, and whether you can search each one's documents directly. Free.

  2. 2

    Ask a question and request citations

    prompt
    Ask the HR Handbook expert how many vacation days a new employee gets. Cite the sources.

    Expect: the expert's answer with citations that link to supporting documents. It is charged once, at the expert's normal Chat.co rate. Expert answers can take longer than an ordinary chat reply; while it waits, the app may check back on the same question several times, and you are still charged once. Answers do not include credit-cost notes; your usage appears in Chat.co.

  3. 3

    Follow up in the same conversation

    prompt
    Does that change after two years of service?

    Expect: an answer that builds on the previous one, because the app continues the same expert conversation. If the reply ignores the earlier context, ask the app to continue the same Chat.co conversation.

  4. 4

    Open a source

    prompt
    Open the source for the first citation.

    Expect: the cited passage in the conversation, or a link to a Chat.co supporting-document page. Private documents ask you to sign in with the account that received the answer. Opening sources is free, even when credits have run out.

  5. 5

    Optional: search documents directly

    prompt
    Search the HR Handbook expert's documents for "parental leave".

    Expect: a list of matching sources you can open. This works only for experts marked as directly searchable. Each completed search costs 0.5 message credit, even when nothing matches.

6. Message credits

ActivityCharge
Ask an expert (including follow-ups)The expert’s normal Chat.co message rate
Completed standalone document search0.5 message credit
Retrieval an expert performs inside its answerNo additional charge
List experts or open returned sourcesFree

A search that completes with no matches still counts. Failed operations, inaccessible experts and retries of the same operation are not charged again. Your existing allocation applies; there is no checkout inside the connector. When credits run out, new paid requests stop, but you can still list experts and open sources you already received.

7. Common errors

What you seeCause and fix
There is no Developer mode settingYour plan or workspace policy does not allow it. Ask your ChatGPT workspace admin.
ChatGPT cannot create the connectionCheck that the URL is exactly https://mcp.chat.co/mcp, authentication is OAuth, registration is dynamic and OIDC is off.
ChatGPT answers without using Chat.coSelect Chat.co from + → Developer mode in that conversation, or name it: “Use Chat.co to ask my experts…”.
Tools look out of dateOpen the connection at chatgpt.com/plugins and select Refresh, then start a new conversation.
“This connection request expired or could not be verified.”The sign-in link was stale or already used. Start the connection again from the app.
“No accessible workspace” on the approval pageThis login has no workspace with expert access. Sign in with the right account, or ask the account owner for access.
An expert is missing from the listYou chose a different workspace, or your access or licence changed. Check the expert in Chat.co, then disconnect and reconnect with the right workspace.
“Expert unavailable.”The expert is not available to this connection. Ask the app to list your experts again and pick one from that list.
“This expert has insufficient message credits…”The allocation is used up. Listing experts and opening sources still work. Add credits through your usual Chat.co process.
“The selected account does not have an active subscription.”The workspace’s Chat.co plan is not active. The account owner can check billing in Chat.co.
“The expert took too long. This operation was not charged.”Try again, or split a very broad question into smaller ones.
Search returns nothing, or asks which expert should payName one expert in the request. Direct search works only for experts marked as searchable.
“This document is unavailable or you no longer have access.”Sign in to Chat.co with the account that received the answer. Removed access or a deleted source cannot be opened.

8. Disconnect

  1. 1

    Revoke access in Chat.co

    Open Connected applications in Chat.co, find the app and workspace, and choose Disconnect. The app loses access to the connector from its next request.

  2. 2

    Remove the server from the app

    In ChatGPT, open chatgpt.com/plugins, select the Chat.co connection and remove it.

Disconnecting stops future access. It cannot remove answers or excerpts the app already received; that app's own terms and privacy policy govern them. To reconnect, start again from the app.

9. For developers & agents

You don't need this section to use Chat.co from an AI app. It documents the protocol for developers and for agents that call the tools directly.

Server

PropertyValue
endpointhttps://mcp.chat.co/mcp
transportMCP Streamable HTTP, stateless. POST only; GET and DELETE return 405 because there is no session to resume.
authOAuth authorization code with PKCE and dynamic client registration. Discovery starts from https://mcp.chat.co/.well-known/oauth-protected-resource, which the server also advertises in its 401 response.
scopechatco:read
authorizationRe-checked on every call: current workspace membership, expert access, licence and credits.

Tools

ToolArgumentsReturnsCost
list_authorized_expertsNoneexperts[] with id, name, description, access.chat and access.knowledgeSearchFree
consult_expertexpert_id*, question* (≤16,000 chars), operation_id* (16–128 letters, digits, - or _), conversation_idconversation_id, answer, citations[] (id, title, url), and files[] (same fields) only when a requested expert action produced an assessment or fileExpert’s normal rate, once
searchquery* (≤8,000 chars), operation_id*, expert_id, paying_expert_idresults[] (id, title, url)0.5 credit per completed search
fetchid*, titleid, title, text (bounded excerpt), url, metadata (expert, page range when known)Free

* Required.

Recipe for agents

  1. 1

    List experts first

    Call list_authorized_experts. Only use id values it returns. Offer search only for experts whose access.knowledgeSearch is true.

  2. 2

    Consult with a fresh operation_id

    Generate a new identifier (a UUID works) for each new question. Keep the returned conversation_id.

    consult_expert argumentsjson
    {
      "expert_id": "<id from list_authorized_experts>",
      "question": "How many vacation days does a new employee get? Cite the sources.",
      "operation_id": "7f3b2c1e-5a9d-4e6f-8b0a-2d4c6e8f1a3b"
    }
    result (abridged)json
    {
      "conversation_id": "<keep for follow-ups>",
      "answer": "New employees receive … [1]",
      "citations": [
        {
          "id": "<source id>",
          "title": "Employee handbook",
          "url": "<source link>"
        }
      ]
    }
  3. 3

    Follow up in the same conversation

    Pass the conversation_id back with a new operation_id.

    consult_expert argumentsjson
    {
      "expert_id": "<same expert>",
      "conversation_id": "<conversation_id from the first answer>",
      "question": "Does that change after two years of service?",
      "operation_id": "c41e9d27-0b6a-4f38-9e15-7a2d8c3b6f90"
    }
  4. 4

    Read evidence with fetch

    Pass the citation's id and its title. The title is shown in approval prompts; the id is the lookup key. The excerpt may not be the whole document.

    fetch argumentsjson
    {
      "id": "<source id from the citation>",
      "title": "Employee handbook"
    }
  5. 5

    Present the answer with its links

    Show every cited source as a link to its url. Offer entries under files as downloads, not as citations. Don't add credit rates, model names or internal configuration to the answer.

Synthetic example: the HR Handbook expert, its answer and the angle-bracket values are placeholders. Use the identifiers and source links the server actually returns.

10. References

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