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The one-line version

Yambr’s public API is MCP only. You get a sandbox, tools, and file hosting. You bring the model.

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What’s behind api.yambr.com

PathPublic?What it is
POST /mcp/computer_useYesMCP over Streamable HTTP. Authenticate with your Yambr key.
GET /mcp-infoYesTool list, required headers, endpoint URL.
POST /v1/chat/completionsNoClosed. Not a resell endpoint.
POST /v1/completionsNoClosed.
POST /v1/embeddingsNoClosed.
GET /v1/modelsNoClosed.
Everything under /v1/* is internal plumbing — it’s there because api.yambr.com is a LiteLLM deployment under the hood, but we don’t publish those paths to end users.

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Why MCP-only

A Yambr key costs us compute (Docker sandboxes, disk for artifacts, bandwidth for browser streaming) but not tokens. Tokens are paid by you to the model provider you pick. This keeps two things clean:
  • Billing is local to each provider. OpenAI bills you for OpenAI usage; we bill you (eventually) for sandbox time. No opaque markup from us reselling inference.
  • Model choice stays yours. New model drops? Use it the day it ships, without waiting for us to add it to a gateway. Fine-tunes, private endpoints, self-hosted vLLM — all work the same way.

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How “bring your own model” actually looks

Concretely, you have two kinds of LLM traffic in your app:
  1. Model calls — client.chat.completions.create(...) — these go to your provider with your key. The provider can be OpenAI, Anthropic, Google, a self-hosted LiteLLM, a fine-tune endpoint, anything.
  2. Tool calls — when the model wants to run bash_tool, view, create_file, str_replace, or sub_agent, the framework sends that to Yambr’s MCP endpoint with your Yambr key.
Every mature agent framework has a clean split for this. Examples:
  • Claude Desktop — model is your Anthropic subscription; Yambr goes under mcpServers in claude_desktop_config.json.
  • OpenAI Agents SDK — model is your OpenAI key on the Agent; Yambr goes in mcp_servers=[MCPServerStreamableHttp(...)].
  • LangChain / LangGraph — model is your chat model binding; Yambr is an MCP tool via MultiServerMCPClient.
  • LiteLLM (self-hosted) — model routes you already have; Yambr added under mcp_servers in config.yaml.
  • n8n — model is the AI Agent node’s credential; Yambr is the MCP Tool node.
  • Cursor — your Cursor subscription runs the model; Yambr is an MCP server in settings.json.

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FAQ

“So I still need an OpenAI / Anthropic key?” Yes — or any OpenAI-compatible key. The Yambr key does not give model access. “What about chat.yambr.com? Isn’t that running models?” Yes — chat.yambr.com is a hosted Open WebUI with models we pay for, as a convenience for browser users. That’s not exposed as a public API. “Can I use sub_agent (Claude Code) without an Anthropic key?” The sub_agent tool launches Claude Code inside the sandbox. It needs an ANTHROPIC_AUTH_TOKEN — in managed Yambr we supply that for you inside the sandbox env for the hosted Claude Code runs; self-hosters set it in .env. See Claude Code gateway. “Will you ever open /v1/chat/completions?” No plan to. The MCP-only surface is the product.