JustOneAPI MCP Server

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Use JustOneAPI in MCP clients such as ChatGPT, Codex, Cursor, Hermes Agent, and
other AI assistant tools.

JustOneAPI MCP helps your assistant find the right JustOneAPI endpoint, inspect
the required parameters, and call APIs through your JustOneAPI authorization.

Supported Clients

JustOneAPI MCP supports remote Streamable HTTP and local stdio. Current verified
and compatibility paths include:

• ChatGPT web custom MCP connections: explicitly select DCR in advanced OAuth
  settings. An existing DCR connection has been verified with a catalog read.
• Codex CLI and the Codex IDE extension: explicit DCR OAuth, verified.
• Cursor, Hermes Agent, and other clients with custom headers: existing API
  Token compatibility method.
• Claude.ai, Claude Desktop, and Claude Code: OAuth remains under compatibility
  testing; Claude Code can use an existing API Token header.

As of October 22, 2026, ChatGPT CIMD connections can fail during authorization
and are temporarily not recommended. Entering the URL and choosing OAuth alone
can select CIMD automatically. A working DCR connection does not establish CIMD
compatibility. CIMD guidance will resume after server-side network access and
the complete authorization flow have been verified; migration alone does not
establish availability. Existing working DCR connections can remain in use.

Compatibility depends on OAuth registration support and account or workspace
policy. Clients without OAuth can keep using a legacy API Token header or local stdio.

Quick Start

Remote HTTP with OAuth

Production supports DCR OAuth. Use this URL and explicitly select DCR using the
client instructions below:

https://mcp.justoneapi.com/mcp

Compatible clients discover the protected-resource metadata, redirect you to
auth.justoneapi.com, and ask for the MCP scopes shown on the consent page.
No JustOneAPI API Token needs to be pasted into the client. Entry points, OAuth
registration methods, and account restrictions vary by client. ChatGPT discovery
can prefer CIMD, so check the selected registration method.

Client setup

• ChatGPT web: enable Developer mode in settings if your account requires it.
  Open Plugins and select + → Add custom MCP server. Enter a name, description,
  and the /mcp URL above. Choose OAuth, expand Advanced OAuth settings, and
  wait for discovery. Set Registration method to Dynamic Client Registration (DCR).
  Confirm Registration URL is https://auth.justoneapi.com/oauth2/register, select
  the scopes you need, then create and install the plugin. No client ID, client
  secret, or static API Token is required. Sign in to JustOneAPI and approve access
  when connecting or invoking a protected tool. If DCR is unavailable, use the Codex
  DCR setup below or contact support instead of repeatedly retrying default CIMD.
• Codex CLI / IDE extension: run the commands below. The currently
  recommended setup explicitly uses the verified DCR registration path:

codex mcp add justoneapi \
  --url https://mcp.justoneapi.com/mcp

codex mcp login justoneapi \
  --oauth-client-registration dcr

Codex CLI and the Codex IDE extension share MCP configuration. ChatGPT web
connections are configured separately and do not inherit the DCR choice from a
Codex login. See the
official OpenAI MCP documentation
and OpenAI authentication documentation.

An authorization request with client_id=https://chatgpt.com/oauth/client.json
uses CIMD. Check the registration method in advanced settings. Other problems can
also cause invalid_request. If DCR fails, send support the time, registration
method, and error message without API Tokens, authorization codes, or other credentials.

OAuth for Claude.ai, Claude Desktop, and Claude Code remains under compatibility
testing and is not yet offered as a generally supported OAuth connection.
Claude Code can use an existing API Token with
--header "Authorization: Bearer your_token"; do not treat the generic JSON
below as a Claude Code configuration.

The authorization page shows the requested scopes. An account owner selects an
existing API Token or creates a dedicated one; a Token Member can only use the
Token assigned to that member. Disconnecting the app later revokes only its
OAuth connection; it does not disable or delete the linked API Token.

Remote HTTP with an existing API Token

The existing header-based connection remains supported for compatibility:

{
  "mcpServers": {
    "justoneapi": {
      "url": "https://mcp.justoneapi.com/mcp",
      "headers": {
        "Authorization": "Bearer your_token"
      }
    }
  }
}

Local stdio

As of 2026-08-25, npm latest is still the legacy 1.0.1 package, not the v2
implementation in this repository. If you require local stdio, pin the version
so the legacy CLI is not mistaken for the hosted v2 service:

{
  "mcpServers": {
    "justoneapi": {
      "command": "npx",
      "args": ["-y", "[email protected]"],
      "env": {
        "JUSTONEAPI_TOKEN": "your_token"
      }
    }
  }
}

Legacy 1.0.1 supports Node.js 18 or newer, and its tool layout is not the same as
the hosted v2 service. OAuth applies only to the remote Worker; stdio continues
to read JUSTONEAPI_TOKEN locally. Update this version guidance after v2 is
actually published to an npm dist-tag.

Catalog builds and dynamic releases use built-in public-safety validation and require no operator
security registry or secret. Runtime API and account calls return the upstream payload without
MCP-layer response truncation.

Authentication and scopes

OAuth users select the API Token to link on the authorization page and do not
paste it into the client. The existing API Token remote compatibility method
uses:

Authorization: Bearer your_token

or, for local stdio:

JUSTONEAPI_TOKEN=your_token

Local stdio uses the environment variable above. Never commit a real Token to a
repository.

OAuth access tokens use three least-privilege scopes:

• mcp:catalog:read — search endpoints, inspect schemas, and list platforms.
• mcp:api:call — call a JustOneAPI endpoint.
• mcp:account:read — view balance and usage.

call_endpoint may incur charges under the API Token linked during OAuth and
its current pricing, permissions, balance, and budget. It validates the
endpoint and parameters before obtaining a short-lived delegation token, then
makes exactly one upstream dispatch. It does not automatically retry an
uncertain timeout, network failure, or HTTP 502/503/504 result.

Legacy API Tokens are still sent to the JustOneAPI backend in the established
query/form format. OAuth access and delegation tokens are never put in backend
URLs or form bodies; delegation tokens are sent only as an Authorization Bearer
header.

Operator rollout

Production currently runs in dual mode. OAuth is additive and feature-flagged,
and these switches remain the deployment and rollback boundary:

• JUSTONEAPI_OAUTH_MODE=off keeps the remote service legacy-only and hides
  OAuth discovery metadata.
• JUSTONEAPI_OAUTH_MODE=dual accepts both existing API Tokens and standard
  OAuth on the exact https://mcp.justoneapi.com origin.
• Preview and workers.dev routes remain legacy-only, even if the variable is
  set to dual.

The Worker uses private_key_jwt for Authorization Server introspection and
RFC 8693 token exchange. Store the private JWK set and active kid as Worker
secrets; never commit .dev.vars, PEM files, or private JWK sets. Rotate keys by
publishing old and new public keys first, switching the active kid second, and
removing the retired key only after the overlap period.

npm 2.0 will first be published under the next dist-tag through OIDC trusted
publishing. After the exact published artifact passes the Node.js 20, 22, and
24 smoke checks, an operator promotes it separately with npm 2FA using
npm dist-tag add [email protected] latest. This is never automated with an
NPM_TOKEN. See RELEASE.md.

Things You Can Ask

Ask your MCP client naturally:

Find the Xiaohongshu note comments API and tell me which parameters are required.

More examples:

Which Douyin APIs can get video details?

Call the Xiaohongshu note comments API with this note ID: xxxxx.

List the Weibo search-related APIs and explain when to use each one.

Continue to the next page of results.

Check my JustOneAPI balance.

Show my recent API usage and spending.

The API returned code 400. Help me check which parameter might be wrong.

The API returned code 601 or 602. What does it mean?

The assistant can search available JustOneAPI endpoints, explain required
parameters, call the selected API after you provide the needed values, and help
interpret common response codes.

License

MIT