# OpenMEP duct sizing (npm · @openmep/mcp)

Deterministic HVAC duct sizing: size one run or a supply/return network, grade existing sections.

- Trust score: 69/100 (medium)
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-26

## Components

- npm · `@openmep/mcp`: 69/100 (this document), [markdown](https://verifymcp.io/servers/samarmstrong-openmep/openmep-mcp.md), [page](https://verifymcp.io/servers/samarmstrong-openmep/openmep-mcp)

## Channel facts

- Registry: `npm`
- Package: `@openmep/mcp`
- Version: `0.1.0`
- Transport: `stdio`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, 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 2026-09-26.

- **Supply Chain Security**: 98/100
  - No malware found by supply-chain analysis.
  - No known CVEs affecting this package version or its production dependencies.
  - No install/post-install scripts declared.
  - 32 of 96 dependencies flagged as unhealthy.
- **Provenance & Transparency**: 45/100
  - Source repository is publicly reachable at the declared URL.
  - Provenance check failed: no build-provenance attestation is published.
  - Clear OSI-approved license (MIT).
  - Actively maintained (last published 3 days ago).
  - Disclosure check failed: no security disclosure policy was found in the source repository.
- **Schema Quality & AI Usability**: 71/100
  - AI-judged instruction clarity (excellent).
  - Context-footprint check failed: tool/resource definitions use about 379 tokens (~189/item across 2 items; 2 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 0/100
  - Stability not yet verified: not enough scan history yet (needs a 30-day window).
- **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 2 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 3 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

**Unverified: 1 category.** A category scored 0 because we could not verify it: a data source with nothing on this package, evidence we could not reach, or a check we could not run. We only credit what we can confirm.

## Install

### How do I install the OpenMEP duct sizing MCP server?

OpenMEP duct sizing runs locally as an npm package, launched with npx -y @openmep/mcp. 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 samarmstrong-openmep -- npx -y @openmep/mcp
```

### Cursor

```json
{
  "mcpServers": {
    "samarmstrong-openmep": {
      "command": "npx",
      "args": [
        "-y",
        "@openmep/mcp"
      ]
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "samarmstrong-openmep": {
      "command": "npx",
      "args": [
        "-y",
        "@openmep/mcp"
      ]
    }
  }
}
```

### Codex

```bash
codex mcp add samarmstrong-openmep -- npx -y @openmep/mcp
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "samarmstrong-openmep": {
      "type": "local",
      "command": [
        "npx",
        "-y",
        "@openmep/mcp"
      ],
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add samarmstrong-openmep --command npx --arg -y --arg @openmep/mcp
```

### Hermes

```yaml
mcp_servers:
  samarmstrong-openmep:
    command: "npx"
    args: ["-y", "@openmep/mcp"]
```

### Netclaw

```json
{
  "McpServers": {
    "samarmstrong-openmep": {
      "Transport": "stdio",
      "Command": "npx",
      "Arguments": [
        "-y",
        "@openmep/mcp"
      ]
    }
  }
}
```

### Vellum

```bash
assistant mcp add samarmstrong-openmep -t stdio -c npx -a -y @openmep/mcp
```

### Other

```json
{
  "mcpServers": {
    "samarmstrong-openmep": {
      "command": "npx",
      "args": [
        "-y",
        "@openmep/mcp"
      ]
    }
  }
}
```

## 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.

### 2026-09-25 (score 69, 0)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

### 2026-09-23 (score 69, +15)

- [security improvement] Malware scan: unverified → pass

### 2026-09-22 (score 54)

First indexed and scored.

## MCP tools (2)

### `size_duct` (~146 tokens)

Size one duct

Recommend a standard round diameter for one duct run carrying a given CFM, with velocity and friction at that size. Optionally grade an existing round, rect, or oval section as ok, undersized, or oversized.

Input parameters:

- `airflowType` (string): System, which sets the velocity cap. Default supply.
- `cfm` (number, required): Airflow the run carries, CFM.
- `existing`: Existing section to grade: { diameterIn } for round, or { shape: rect|oval, widthIn, heightIn }.
- `role` (string): main (at equipment), branch (serves several terminals), or runout (one terminal). Default main.

### `size_duct_network` (~120 tokens)

Size a duct network

Size every supply, return, exhaust, and outside-air segment of a connected duct network. Each terminal's requiredCfm is carried along its shortest same-system path to equipment and summed per segment; roles (main/branch/runout) are inferred. Returns per-segment recommendations, grades for segments with an existing section, and findings: missing-required-cfm, no-equipment-path, dangling-reference, mixed-system-segment, undersized, oversized.

Input parameters:

- `items` (array, required): Every terminal, segment, fitting, and equipment item in the network.

## Diagnostics

Captured diagnostic sections: Provenance, Dependencies. The full working is on the page: https://verifymcp.io/servers/samarmstrong-openmep/openmep-mcp#diagnostics

## Score history

- 2026-09-26: 69
- 2026-09-25: 69
- 2026-09-24: 69
- 2026-09-23: 69
- 2026-09-22: 54

## Common questions

### What is the OpenMEP duct sizing MCP server?

OpenMEP duct sizing is an MCP server listed in the public MCP registry as io.github.samarmstrong/openmep. Deterministic HVAC duct sizing: size one run or a supply/return network, grade existing sections. This page covers its npm package (@openmep/mcp).

### Is the OpenMEP duct sizing MCP server safe to use?

OpenMEP duct sizing scores 69 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 26 September 2026. It declares no install or post-install scripts. 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 OpenMEP duct sizing MCP server expose?

OpenMEP duct sizing exposes 2 tools: size_duct, size_duct_network. Their descriptions and schemas cost roughly 266 tokens of context every time the server is loaded.

### Is the OpenMEP duct sizing MCP server still maintained?

OpenMEP duct sizing is still listed as active in the MCP registry. We last reached this channel on 26 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

### What licence is the OpenMEP duct sizing MCP server under?

OpenMEP duct sizing declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.

## Links

- npm package: https://www.npmjs.com/package/@openmep/mcp
- Socket report: https://socket.dev/npm/package/@openmep/mcp
- Repository: https://github.com/samarmstrong/openmep
- Changelog RSS feed: https://verifymcp.io/servers/samarmstrong-openmep/openmep-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/samarmstrong-openmep/openmep-mcp.json
- HTML version of this page: https://verifymcp.io/servers/samarmstrong-openmep/openmep-mcp