LangBot MCP Operations

LangBot exposes an MCP server so AI agents can manage an instance programmatically. It mirrors a curated subset of the HTTP service API.

Endpoint

http://<langbot-host>:5300/mcp

Transport: streamable HTTP (stateless, JSON responses). Same host/port as the web UI and HTTP API.

Authentication

Reuses the same API keys as the HTTP API. Send either header:

X-API-Key: <api-key>
# or
Authorization: Bearer <api-key>

Two kinds of key are accepted:

1. Web-UI key — created in the web UI (sidebar → API Keys), prefixed lbk_. The secret is shown once; only its SHA-256 hash is stored. Each key is bound to one Workspace and has explicit scopes, status, optional expiry, and last-used metadata. The key determines the Workspace; callers cannot switch it with X-Workspace-Id.
2. Global API key — set in data/config.yaml under api.global_api_key. Requires no login session and no DB record; does not need the lbk_ prefix. It is accepted only by a community instance with exactly one local Workspace and is disabled for SaaS multi-Workspace operation. Leave empty to disable. See the langbot-deploy skill for config details.

Invalid, revoked, or expired keys get 401 Unauthorized. A valid key whose scopes do not authorize a tool gets 403 Forbidden.

To inspect key identity and permissions, call GET /api/v1/system/context with the API key.

Client configuration

{
  "mcpServers": {
    "langbot": {
      "url": "http://<langbot-host>:5300/mcp",
      "headers": { "X-API-Key": "<api-key>" }
    }
  }
}

Tool surface

The tools wrap the LangBot service layer. Current tools (v1):

Mutating tools (create_*, update_*) take a JSON object matching the same shape as the corresponding HTTP API request body. Discover resources with the list_* / get_* tools before mutating; identifiers are UUIDs. Reads require resource.view; mutations require resource.manage. All service calls inherit the immutable Workspace context authenticated at the MCP transport boundary. Pass is_default: true to create_pipeline only when the Workspace does not already have a default pipeline.

How to use

1. Get an API key (web UI key, or set api.global_api_key in config.yaml).
2. Point your MCP client at http://<host>:5300/mcp with the key header.
3. Call get_system_info to confirm connectivity.
4. Use list_* tools to discover, then get_* / create_* / update_* / delete_* as needed.

ChatGPT / Codex subscription providers

list_model_providers can return the openai-codex requester. Its OAuth credentials are server-only and are not provider API keys. Never ask a user to paste ChatGPT access tokens, refresh tokens, or a Codex auth cache into an MCP tool or model configuration.

A human connects or disconnects the subscription through Models → provider settings in the LangBot web UI. The provider-scoped /codex/* authentication routes deliberately require a browser-user session and are not exposed as MCP tools or authorized by a LangBot API key. Once connected, models are managed and selected through the normal provider/model workflow. A disconnected provider must be reauthorized; do not silently replace it with API-key billing.

See ChatGPT / Codex subscription for setup, usage limits, and the personal-account versus shared-service boundary.

Provider deletion

The curated MCP surface currently lists providers but has no provider-deletion tool. In the web UI, Edit Provider → Delete asks for confirmation before removing that provider and all its LLM, embedding, and rerank models. This is irreversible; never interpret a request to edit a provider as authorization to delete it.

The equivalent HTTP operation is DELETE /api/v1/provider/providers/{uuid}?cascade=true, requiring resource.manage in the authenticated Workspace. Omitting cascade preserves the existing refusal to delete providers that still have models. Cloud-managed providers remain protected. Cascade deletion removes stored Codex authorization state as well; it is not the same operation as disconnecting an account.

Implementation & maintenance (for LangBot developers)

• Server: src/langbot/pkg/api/mcp/server.py (FastMCP). Tools call the service layer directly, so the MCP surface stays aligned with the API.
• Mount: src/langbot/pkg/api/mcp/mount.py — an ASGI dispatcher fronting Quart, authenticating /mcp requests, running the streamable-HTTP session manager.
• Smoke test: tests/manual/mcp_smoke.py.

When you add, remove, or change an HTTP API endpoint that should be agent-accessible, update the corresponding MCP tool and this skill. The MCP tool surface and the API must stay aligned (see AGENTS.md).

Pitfalls

• /mcp is the server LangBot exposes. The /api/v1/mcp routes are the client side (managing external MCP servers LangBot connects to). Don't confuse them.
• A 401 means the key is wrong, missing, revoked, expired, or (for the global key) api.global_api_key is empty or the instance is not an OSS singleton.
• A 403 means the key is valid but lacks the permission required by the tool.
• The global key is plaintext in config.yaml — only enable it on trusted/internal deployments and serve over HTTPS.