# MCP Tools & API Reference [← Nexus documentation](https://www.plotune.net/docs/nexus) API Reference The actual MCP tool surface an agent calls: real tool names, read-only resources, authentication, and the client setup commands for Claude Code, Codex, Cursor, VS Code, and n8n. API Reference 9 min read Updated 2026-09-26 ## Endpoint Nexus exposes its tool surface over the Model Context Protocol (MCP), HTTP transport: - Direct to a device on your network : `http:///mcp` - Through Plotune's cloud router , device-scoped: `https://nexus.plotune.net/devices//mcp/` The direct path is HTTP-only, because Nexus is a networked device rather than a local stdio process. The router path is HTTPS and owns OAuth discovery plus dynamic client registration for that public endpoint; the device UUID is part of the URL because the router has to resolve the correct device route before it can present that device's OAuth surface. ## Authenticating OAuth is the preferred path. It keeps redirect, consent, and client-registration behavior on the standard, auditable MCP surface, and it's the only path that can grant a session the full owner-level permission set. Some clients fall back from device-scoped OAuth discovery to origin-level paths (`/.well-known/oauth-protected-resource`, `/.well-known/oauth-authorization-server`, `/register`) that don't carry a device UUID, which means the router can't safely infer which device to route to from the URL alone. For those clients, pass the device UUID as a static header instead: ``` { "servers": { "plotune-nexus": { "type": "http", "url": "https://nexus.plotune.net/devices//mcp/", "headers": { "X-Plotune-Device-UUID": "" } } } } ``` Manual bearer tokens are the fallback for clients that can't complete OAuth at all. An authorized device user generates a time-bound token from the device's Security page, then sends it as either `Authorization: Bearer ` or `X-Plotune-MCP-Bearer-Token: `. Manual token generation is unavailable from a degraded local-recovery session; see [Security & Trust Model](https://www.plotune.net/docs/nexus/security-model) for why. OAuth dynamic client registration generally requires HTTPS. A client set to OAuth mode will fail against a plain-HTTP local device deployment before the request even reaches the device, since that's the client's own OAuth library rejecting a non-HTTPS authorization server, not a Nexus restriction. If that happens, switch the client to its static-header / manual-token configuration instead of its OAuth path. ## Client setup Claude Code ``` claude mcp add --transport http plotune-nexus http:///mcp ``` Codex ``` codex mcp add plotuneNexus --url http:///mcp ``` For the cloud router endpoint, Codex's dynamic client registration works directly against the device-scoped URL: ``` codex mcp add plotune-nexus --url https://nexus.plotune.net/devices//mcp/ codex mcp login plotune-nexus ``` VS Code , in `.vscode/mcp.json`: ``` { "servers": { "plotune-nexus": { "type": "http", "url": "http:///mcp" } } } ``` Cursor , in `~/.cursor/mcp.json`: ``` { "mcpServers": { "plotune-nexus": { "url": "http:///mcp" } } } ``` OpenCode , using the manual bearer token path directly (the most reliable route for a local HTTP device deployment): ``` opencode mcp add plotune-nexus --url http:///mcp \ --header "Authorization=Bearer " ``` n8n can call Nexus MCP tools from ordinary workflows, without an LLM in the loop, using n8n's MCP Client node against the same `/mcp` endpoint and bearer-token model. ## Resources vs. tools Nexus separates read-only state from mutating actions. Use resources first for current-state reads, then tools for anything that changes state, transfers data, or runs a longer workflow: - `plotune://device/interfaces`: currently attached/available interfaces - `plotune://device/context`: device identity and runtime status - `plotune://artifacts/recent`: recently produced recordings and artifacts ## Representative tool surface This is not the complete tool list, and the exact signature of any tool can change; it's meant to show the shape of the surface, not serve as a frozen spec. Confirm current tools and their parameters against your own connected device (`get_runtime_capabilities_tool()` and `get_tooling_health_tool()` report what's actually live). | Category | Example tools | | --- | --- | | CAN | create_virtual_can, acquire_can_interface, attach_slcan, configure_can_bitrate, send_dbc_message, wait_dbc_signal, record_can, release_stale_can_leases | | UART | open_uart_session, send_uart, read_uart, record_uart, get_uart_modem_lines, set_uart_modem_lines, close_uart_session | | XCP | record_xcp, read_xcp_calibration, set_xcp_calibration | | DDS / ROS 2 | join_dds_session, list_dds_participants_tool, list_dds_topics_tool, capture_dds_snapshot, publish_dds_message, wait_dds_signal, record_dds_topics, leave_dds_session | | Artifacts | read_artifact, prepare_put_artifact, put_artifact, get_artifact, upload_to_artifact_drive, download_from_artifact_drive | | Orchestration | run_test_sequence | | Containers | start_container (used to run bundled protocol simulators or customer workloads under Nexus's managed container runtime) | `configure_can_bitrate` takes standard CAN timing parameters directly: bitrate, sample point, SJW, and the phase-segment values, rather than only accepting a fixed preset list. ## Job model DAQ operations are asynchronous jobs, not blocking MCP calls, because recording and control work can be slow, stateful, and produce large outputs. A tool call that starts a job returns status, timestamps, and either an inline small result or a retrieval reference for larger artifacts, not the raw data itself for anything nontrivial in size. ## References - [Model Context Protocol specification](https://modelcontextprotocol.io/specification/) - [MCP transport](https://modelcontextprotocol.io/specification/basic/transports), HTTP + OAuth - [OAuth 2.0 Dynamic Client Registration](https://datatracker.ietf.org/doc/html/rfc7591) Plotune Nexus: the appliance these MCP tools run on. [See the product page](https://www.plotune.net/nexus?article=mcp-api&entry_source=direct) More Nexus documentation [SecuritySecurity & Trust Model](https://www.plotune.net/docs/nexus/security-model)[CompatibilityHardware & Protocol Compatibility](https://www.plotune.net/docs/nexus/hardware-compatibility)[ArchitectureSystem Architecture](https://www.plotune.net/docs/nexus/architecture)[DeploymentData Handling & Deployment Model](https://www.plotune.net/docs/nexus/data-handling)[ProtocolsProtocol Notes: CAN, UDS, DoIP, XCP](https://www.plotune.net/docs/nexus/protocols)[OnboardingQuick Start](https://www.plotune.net/docs/nexus/quick-start) Source: https://www.plotune.net/docs/nexus/mcp-api