NreplSAFE
nRepl mcp server for clojure. Enables interaction with a running Clojure nREPL instance, allowing evaluation of Clojure code, namespace inspection, and other utilities via MCP.
Overview
From the repository's own README, as read at the audited commit. Badges and raw HTML are left out.
A Model Context Protocol (MCP) server designed for MCP clients, such as Claude Desktop or CLine in VSCode. This server can be used with any LLM when used with CLine. This server enables interaction with a running Clojure nREPL instance, allowing evaluation of Clojure code, namespace inspection, and other utilities via MCP.
Features
- Connect to a running nREPL server by specifying host and port.
- Evaluate Clojure code in a given namespace or the current one.
- List project namespaces using
tools.namespace. - Retrieve nREPL connection status, including host, port, and session details.
- Inspect public vars in any Clojure namespace, displaying metadata such as docstrings and values.
Installation & Setup
Installing in CLine (VSCode) or Claude Desktop
To use this server with CLine or Claude Desktop, follow these steps:
- Open CLine in VSCode or Claude Desktop.
- Navigate to the MCP Settings.
- Add a new MCP server with the following configuration:
{
"mcpServers": {
"nrepl-mcp-server": {
"command": "npx",
"args": [
"nrepl-mcp-server"
],
"disabled": false,
"autoApprove": []
}
}
}- Save and restart the client to apply changes.
This will allow the client to communicate with the nREPL MCP server via standard input/output.
Install via npx
To quickly run the server without cloning the repository:
npx nrepl-mcp-server
Manual Installation
- Clone the repository
- Install dependencies
npm install
- Build the project (transpiles TypeScript to JavaScript)
npm run build
- Run the server
- Production Mode: Runs from compiled output.
npm start
- Development Mode: Uses ts-node for live changes.
3fdafe12a2acOBSERVED · 2026-10-08Connect
Built from this server's own package name, version and transport as found in its source — not copied from anyone's documentation, so it cannot drift against a page we do not control.
claude mcp add nrepl-mcp-server -- npx -y [email protected]
{
"mcpServers": {
"nrepl-mcp-server": {
"command": "npx",
"args": [
"-y",
"[email protected]"
]
}
}
}Exposed tools (3)
3 read · 0 write · 0 destructive.
| Tool | Risk | Description |
|---|---|---|
connect | read | Connect to an nREPL server.\n |
eval_form | read | Evaluate Clojure code in a specific namespace or the current one. Examples:\n |
get_ns_vars | read | Get all public vars (functions, values) in a namespace with their metadata and current values. Example:\n |
Trust audit
SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.
| Layer | What it checks | Result |
|---|---|---|
| L0 | Provenance & inventory | PASS |
| L1 | Static analysis of the code | PASS |
| L2 | Instruction surface (what it tells the agent) | PASS |
| L3 | Class-specific surface | PASS |
| L4 | Behavioural (sandbox) | SKIPPED |
What the source does
- Filesystem
- none-observed
- Network
- declared (1 observation(s))
- Shell
- none-observed
- Dependencies
- not all pinned
- Secrets in source
- none-found
Findings (2)
@modelcontextprotocol/sdk, ts-node
Gates applied: no_behavioural_pass, no_license.
3fdafe12a2acfull audit observations/trust-audit/mcp-server/johancodinha__nrepl.json · Report an issue / request a re-scanAudit history
Every audit this server has had. A grade with a past is a grade somebody is still checking.
| Date | Source | Verdict | Grade | Score | Change |
|---|---|---|---|---|---|
| 2026-10-08 | 3fdafe12a2ac | SAFE | B | 89 | first audit |
Questions
What is the Nrepl MCP server?
nRepl mcp server for clojure. Enables interaction with a running Clojure nREPL instance, allowing evaluation of Clojure code, namespace inspection, and other utilities via MCP.
What tools does Nrepl expose?
3 in total: 3 read-only, 0 that write, and 0 that can delete or overwrite. Every one is listed on this page with its risk.
Is Nrepl safe to connect to an agent?
The audit found nothing in the source that contradicts what it says it does, and graded it B (89/100). Grade A is held back for packages that have also passed a sandboxed behavioural run, which is why a clean server reads B.
What credentials does Nrepl need?
No credential environment variables were found in its source, so it appears to need none.
How does Nrepl run?
It speaks stdio, so it runs as a local process your client starts. It is published on npm as nrepl-mcp-server at 1.0.2.
How current is this page?
The grade is for one exact copy of the source (3fdafe12a2ac), read on 2026-10-08. The repository is watched and re-audited when it changes.