# DERATE — truck fault codes (remote · derate.app)

Heavy-duty truck SPN/FMI and OBD fault codes: meaning, safe-to-drive verdict, parts and recalls.

- Trust score: 83/100 (high trust)
- Change this week: +3
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-05

## Components

- remote · `derate.app`: 83/100 (this document), [markdown](https://verifymcp.io/servers/app-derate-derate/derate.md), [page](https://verifymcp.io/servers/app-derate-derate/derate)

## Channel facts

- Endpoint: `https://derate.app/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `2.0.0`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-11-05.

- **Endpoint Security**: 80/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one.
  - HTTPS is enforced; there's no plaintext access path.
  - The HSTS (Strict-Transport-Security) header is present.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 76/100
  - AI-judged instruction clarity (good).
  - Context-footprint check failed: tool/resource definitions use about 1660 tokens (~110/item across 15 items; 15 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 80/100
  - Stability observed for 24 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 15 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 16 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 60/100
  - Spec-recency check failed: implements MCP spec 2025-06-18; the latest is 2026-07-28.

## Install

### How do I install the DERATE — truck fault codes MCP server?

DERATE — truck fault codes is a hosted endpoint at https://derate.app/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add --transport http app-derate-derate 'https://derate.app/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "app-derate-derate": {
      "url": "https://derate.app/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "app-derate-derate": {
      "type": "http",
      "url": "https://derate.app/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.app-derate-derate]
url = "https://derate.app/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "app-derate-derate": {
      "type": "remote",
      "url": "https://derate.app/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add app-derate-derate --url 'https://derate.app/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  app-derate-derate:
    url: "https://derate.app/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "app-derate-derate": {
      "Transport": "http",
      "Url": "https://derate.app/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add app-derate-derate -t streamable-http -u 'https://derate.app/mcp'
```

### Other

```json
{
  "mcpServers": {
    "app-derate-derate": {
      "type": "http",
      "url": "https://derate.app/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-11-04 (score 83, +1)

No change was recorded against any check on this day. Stability & Change Management went from 73 to 77. That category is still filling its 30-day observation window: 22 days of observed history at the previous scan, 23 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-11-02 (score 82, +1)

No change was recorded against any check on this day. Stability & Change Management went from 67 to 70. That category is still filling its 30-day observation window: 20 days of observed history at the previous scan, 21 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-31 (score 81, +1)

No change was recorded against any check on this day. Stability & Change Management went from 60 to 63. That category is still filling its 30-day observation window: 18 days of observed history at the previous scan, 19 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-28 (score 80, +1)

No change was recorded against any check on this day. Stability & Change Management went from 50 to 53. That category is still filling its 30-day observation window: 15 days of observed history at the previous scan, 16 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-26 (score 79, +1)

No change was recorded against any check on this day. Stability & Change Management went from 43 to 47. That category is still filling its 30-day observation window: 13 days of observed history at the previous scan, 14 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-24 (score 78, +1)

No change was recorded against any check on this day. Stability & Change Management went from 37 to 40. That category is still filling its 30-day observation window: 11 days of observed history at the previous scan, 12 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-22 (score 77, +11)

- [security improvement] Transport: fail → pass

### 2026-10-21 (score 66, −10)

- [security regression] Transport: pass → fail
- [security] The server rewrote its instructions, which are the text every model session reads
- [functional regression] Schema quality: 1456 → 1660
- [functional] Server version: 2.0.0 → 2.1.0
- [functional] New tool “get_guide”
- [functional] New tool “search_guides”

## MCP tools (15)

### `buscar_codigo` (~100 tokens)

Search truck fault code / Buscar código

Search DERATE's 56-code heavy-truck library by SPN/FMI, P-code or free text. Returns severity, derates yes/no, meaning, part and estimated part-price range, and the page URL. / Busca en la biblioteca de códigos de DERATE.

Input parameters:

- `lang` (string): Response language / Idioma: 'en' or 'es'.
- `query` (string, required): SPN/FMI, P-code or free text.

### `es_seguro_manejar` (~105 tokens)

Is it safe to drive? / ¿Es seguro manejar?

Safe-to-drive verdict (stop / service_soon / info) for a truck fault code, from DERATE's library only. Unknown codes return 'unknown'. / Veredicto de si es seguro seguir manejando.

Input parameters:

- `code` (string, required): e.g. 'SPN 3251 FMI 0', '3251/0', 'P20EE'.
- `lang` (string): Response language / Idioma: 'en' or 'es'.

### `retiros_de_camion` (~119 tokens)

Truck recalls / Retiros de camión

How to check heavy-truck safety recalls (NHTSA-based), with per-make source links for Freightliner, Volvo, Kenworth, Peterbilt, International, Mack and Western Star. / Cómo revisar retiros de seguridad.

Input parameters:

- `lang` (string): Response language / Idioma: 'en' or 'es'.
- `limit` (integer): Maximum items.
- `make` (string): Optional truck make, e.g. 'Volvo'.
- `query` (string): Optional free text, e.g. a make.

### `get_data_notes` (~68 tokens)

Data quality notes / Notas de calidad de datos

DERATE dataset notes: code count, sources, known gaps, license (CC BY 4.0), how to cite and download URLs. / Notas de calidad, licencia y cómo citar.

Input parameters:

- `lang` (string): Response language / Idioma: 'en' or 'es'.

### `search_guides` (~97 tokens)

Search guides and news / Buscar guías y noticias

Search DERATE's truck-driver guides and trucking news (derate, DEF, emissions, recalls, enforcement, market). Returns title, quick answer and derate.app URL. / Busca en las guías y noticias de DERATE.

Input parameters:

- `lang` (string): Response language / Idioma: 'en' or 'es'.
- `query` (string, required): Words to search for, e.g. 'derate' or 'DEF'.

### `get_guide` (~84 tokens)

Get a guide or news article / Ver guía o noticia

Full text (markdown) of one DERATE guide or news article by slug, with sources and the derate.app URL to cite. / Texto completo de una guía o noticia.

Input parameters:

- `lang` (string): Response language / Idioma: 'en' or 'es'.
- `slug` (string, required): Article slug, e.g. 'what-is-engine-derate'.

### `get_truck_fault_code` (~189 tokens)

Get truck fault code

Look up a diesel truck fault code (J1939 SPN/FMI such as 'SPN 3251 FMI 0', or an OBD-II code such as 'P2002') in DERATE's public fault-code library. Returns what the code means, its severity, whether it is safe to keep driving, probable causes, the recommended tests, and the canonical URL of the public page for that code. Works without any account.

Input parameters:

- `code` (string, required): The fault code, e.g. 'SPN 3251 FMI 0', '3251/0' or 'P2002'.
- `engine_family` (string): Optional engine family for context, e.g. 'cummins', 'paccar-mx', 'detroit'.
- `lang` (string): Response language: 'es' (Spanish) or 'en' (English).

### `interpret_derate` (~166 tokens)

Interpret an engine derate

Explain a diesel truck engine derate or power-loss symptom described in plain language (for example 'DEF light on and truck limited to 55 mph'). Returns the most likely cause, how urgent it is, the immediate action to take, and matching public fault-code pages. This is the free public interpretation; the full guided diagnosis with tests and a work order runs in the DERATE app.

Input parameters:

- `code` (string): Optional fault code already known (SPN/FMI or OBD-II).
- `engine_family` (string): Optional engine family, e.g. 'cummins'.
- `lang` (string): Response language: 'es' (Spanish) or 'en' (English).
- `symptom` (string, required): Free-text symptom, warning light or behavior the driver observes.

### `search_fault_code_library` (~121 tokens)

Search the fault code library

Full-text search over DERATE's public diesel truck fault-code library by code, system, dashboard light or symptom words. Returns a list of matching entries with code, title, severity, system and the canonical public URL.

Input parameters:

- `lang` (string): Response language: 'es' (Spanish) or 'en' (English).
- `limit` (integer): Maximum results.
- `query` (string, required): Code or free text to search for.
- `severity` (string): Optional severity filter: RED stop now, YELLOW caution, WHITE info only.

### `list_supported_engine_families` (~54 tokens)

List supported engine families

List the diesel truck engine families and code protocols DERATE interprets (J1939 SPN/FMI and OBD-II), so an agent knows whether a given truck is covered before looking up a code.

### `get_pricing` (~59 tokens)

Get DERATE pricing

List DERATE's plans and prices in USD. The app is a free download; plans are purchased inside the iOS/Android app (App Store / Google Play). Monthly Driver and Shop plans include a 7-day free trial for new subscribers.

### `get_download_links` (~39 tokens)

Get DERATE download links

Return the official App Store and Google Play links for the DERATE native app (iOS and Android). DERATE runs only as a mobile app.

### `get_diagnosis` (~68 tokens)

Get diagnosis

Return the full DERATE demo diagnosis for a truck: verdict (STOP/CAUTION/CLEAR), derate countdown, every fault code and the work order summary.

Input parameters:

- `lang` (string): Language of the diagnosis text: 'es' (Spanish) or 'en' (English).

### `list_fault_codes` (~58 tokens)

List fault codes

List the fault codes (SPN/FMI) in the current DERATE diagnosis with severity, system, fault type and whether they are a root cause.

Input parameters:

- `lang` (string): Language of the labels: 'es' or 'en'.

### `explain_fault_code` (~91 tokens)

Explain fault code

Explain a truck fault code or symptom in DERATE terms: plain-language meaning, severity, probable causes, recommended tests with expected values, repair steps and cost estimate.

Input parameters:

- `lang` (string): Language of the explanation: 'es' or 'en'.
- `query` (string, required): Fault code (e.g. 'SPN 3251 FMI 0'), system name or symptom text to look up.

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/app-derate-derate/derate#diagnostics

## Score history

- 2026-11-05: 83
- 2026-11-04: 83
- 2026-11-03: 82
- 2026-11-02: 82
- 2026-11-01: 81
- 2026-10-31: 81
- 2026-10-30: 80
- 2026-10-29: 80
- 2026-10-28: 80
- 2026-10-27: 79
- 2026-10-26: 79
- 2026-10-25: 78
- 2026-10-24: 78
- 2026-10-23: 77
- 2026-10-22: 77
- 2026-10-21: 66
- 2026-10-20: 76
- 2026-10-19: 75
- 2026-10-18: 75
- 2026-10-17: 74
- 2026-10-16: 74
- 2026-10-15: 73
- 2026-10-14: 73
- 2026-10-13: 73
- 2026-10-12: 72

## Common questions

### What is the DERATE — truck fault codes MCP server?

DERATE — truck fault codes is an MCP server listed in the public MCP registry as app.derate/derate. Heavy-duty truck SPN/FMI and OBD fault codes: meaning, safe-to-drive verdict, parts and recalls. This page covers its hosted endpoint (https://derate.app/mcp).

### Is the DERATE — truck fault codes MCP server safe to use?

DERATE — truck fault codes scores 83 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the DERATE — truck fault codes MCP server expose?

DERATE — truck fault codes exposes 15 tools: buscar_codigo, es_seguro_manejar, retiros_de_camion, get_data_notes, search_guides, and 10 more. Their descriptions and schemas cost roughly 1,418 tokens of context every time the server is loaded.

### Does the DERATE — truck fault codes MCP server require authentication?

No. We connected to DERATE — truck fault codes without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the DERATE — truck fault codes MCP server still maintained?

DERATE — truck fault codes is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- Remote endpoint: https://derate.app/mcp
- Website: https://derate.app/
- Changelog RSS feed: https://verifymcp.io/servers/app-derate-derate/derate.xml
- Changelog JSON feed: https://verifymcp.io/servers/app-derate-derate/derate.json
- HTML version of this page: https://verifymcp.io/servers/app-derate-derate/derate