MCP

arbitr exposes the published /v1 API as a hosted MCP server so a coding agent can call it as tools. Auth is the same API key as curl and the CLI — there is no OAuth login yet.

Use the CLI for files on disk. MCP submit takes a public https URL, not a local path.

Endpoint

https://api-arbitr.straker.ai/mcp/

Streamable HTTP. Include the trailing slash. After you connect, the client lists the tools. They map to published /v1 operations. Deprecated HTTP aliases are not tools.

Auth

Mint a key under Settings → API Keys. See Create an API key. For submit, poll, and download the key needs both verify:submit and verify:read. Send it on every MCP request as either:

X-API-Key: abr_live_…

or Authorization: Bearer abr_live_…. A missing key fails at connect (401). Prefer interpolating ARBITR_API_KEY from the environment so the key is not committed or pasted into chat.

A test key (abr_test_…) works the same way. It does not run the pipeline — read Test mode first.

Check the key with getCurrentKey (or arbitr me) before you submit. That call works with any valid key.

Cursor

Merge this into .cursor/mcp.json (project) or ~/.cursor/mcp.json (user). Do not replace unrelated servers.

{
  "mcpServers": {
    "arbitr": {
      "url": "https://api-arbitr.straker.ai/mcp/",
      "headers": {
        "X-API-Key": "${env:ARBITR_API_KEY}"
      }
    }
  }
}

Set ARBITR_API_KEY the same way as the CLI. Reload MCP if the server does not appear.

Claude Code

claude mcp add --transport http arbitr https://api-arbitr.straker.ai/mcp/ \
  --header "X-API-Key: ${ARBITR_API_KEY}"

The shell must already export ARBITR_API_KEY. Do not put the plaintext key on the command line.

Tools

CamelCase names match the published /v1 operationIds. A new REST route does not become a tool until it is registered.

Tool	Does	Scope
`submitProject`	Create a project from a public `https` `file_url`	`verify:submit`
`getProject`	Poll one project's status	`verify:read`
`listProjects`	List projects (`page`, `limit`, optional `status`, `modified_after`)	`verify:read`
`listDeliverables`	List files for a completed project; returns download URLs, not bytes	`verify:read`
`createProjectResumption`	Resume after an intelligence-credit hold	`verify:submit`
`createReviewResumption`	Resume after a trust-credit hold	`verify:submit`
`listLanguages`	Supported lowercase BCP-47 codes	any valid key
`getCreditBalance`	Intelligence and trust balances	any valid key
`getCurrentKey`	Org, mode, and scopes for this key	any valid key

Webhooks, MT models, and deprecated verb-path aliases (/resume, /deliverables/zip) are not tools.

Submit vs the CLI

submitProject fetches one source file from a public https file_url after the key is validated. Local paths, inline bytes, and http URLs are rejected. For a file on disk, or more than one file, use arbitr submit or Create a project.

The fetch is capped at 25 MB (REST multipart allows 200 MB). Larger files need the CLI or REST.

Argument	Required	Notes
`file_url`	yes	Public `https` URL of the source document
`name`	yes	Shown in the arbitr UI
`source_language_code`	yes	Lowercase BCP-47, e.g. `en-us`
`target_language_codes`	yes	List of lowercase BCP-47 tags
`workflow`	yes	`AI_TRANSLATION` first; optional `TRANSLATION`, `EDIT`
`due_date`	no	`YYYY-MM-DD`. Informational only
`filename`	no	Override; otherwise derived from the URL
`idempotency_key`	no	Same contract as REST `Idempotency-Key` — see Idempotency

The call spends credits. Locales are lowercase BCP-47 (ko-kr, not ko). Use listLanguages for the exact bcp47 values.

Typical flow

submitProject — copy id from the result.
Poll getProject until a terminal status. Stop on completed (download), failed / cancelled (stop), or awaiting_payment (top up, then createProjectResumption or createReviewResumption). See Poll project status.
listDeliverables once status is completed. Each item has a key-gated download_url. The payload also has zip_download_url.
Fetch those URLs with the same API key. For a single file, send Accept: application/octet-stream to get bytes rather than metadata. See Download deliverables.

Sleep a few seconds between getProject calls. Tight loops hit rate limits.

Failures

What you see	Typical cause
HTTP `401` `invalid_api_key` at connect	Missing `X-API-Key` / `Authorization: Bearer`
Tool error `invalid_api_key`	Unknown or revoked key
Tool error `missing_scope: verify:submit`	Key lacks `verify:submit`
Tool error with `422` / `402` / `429`	Same as the matching `/v1` failure

Keep request_id if you contact Support.

Coding agents

This page is the MCP playbook. Fetch it as markdown:

https://arbitr.apidocumentation.com/getting-started/mcp/index.md

Do not submit a project during setup. Confirm the key with getCurrentKey (or arbitr me) first.

Agent skill

Authentication & scopes