Hosted deployment
A hosted deployment is available on Fronteir AI.
Quick Start
npx (any MCP client)
{
"mcpServers": {
"memorylens": {
"type": "stdio",
"command": "npx",
"args": ["-y", "memorylens-mcp"]
}
}
}
The npm package ships no server code — it is a launcher that installs the MemoryLens.Mcp .NET
global tool at a matching version and execs it, so the .NET 10 SDK must be on PATH.
Subsequent starts skip the install entirely and work offline.
VS Code / Visual Studio (via dnx)
Add to your MCP settings (.vscode/mcp.json or VS settings):
{
"servers": {
"memorylens": {
"type": "stdio",
"command": "dnx",
"args": ["MemoryLens.Mcp", "--yes"]
}
}
}
Claude Code Plugin
claude install gh:MarcelRoozekrans/memorylens-mcp
.NET Global Tool
dotnet tool install -g MemoryLens.Mcp
Docker
docker build -t memorylens-mcp .
docker run -i --rm --pid=host --cap-add=SYS_PTRACE \
-v /tmp:/tmp \
-v "$PWD:/workspace" memorylens-mcp
Profiling from a container needs ptrace and the host PID namespace, and on
Docker Desktop that namespace is the Linux VM rather than your desktop — see
docs/docker.md before choosing this route.
-v /tmp:/tmp is what makes list_processes return anything — the runtime's
diagnostic sockets live in the temp directory — and it is also what keeps
snapshots alive after --rm, since they are written to
/tmp/memorylens-snapshots inside the container. -v "$PWD:/workspace" is only
so .memorylens.json is picked up; nothing is written there.
Prerequisites
- .NET 10 SDK, 10.0.4xx feature band (pinned in
global.json)
Running a filtered subset of the tests, e.g. dotnet test --filter <name>, will exit with code 9
and print error: 1, failed: 0. That's the test project's discovery-collapse guard
(--minimum-expected-tests) firing because the filter left fewer tests than expected — it is
not a test failure, and a full dotnet test run is unaffected.
How Collection Works
MemoryLens collects heap data in-process over EventPipe, the .NET runtime's built-in diagnostics channel. There is no profiler to install, no download on first use, and no external tool on PATH.
snapshot attaches to a running .NET process by pid, induces a collection, and aggregates the heap into per-type counts and sizes. Snapshots are written as small JSON files under your temp directory and referenced by a short id.
On Linux and in containers, attaching to another process's diagnostic endpoint may require matching UID or SYS_PTRACE — see docs/docker.md.
Available MCP Tools
| Tool | Description |
|---|---|
list_processes | Lists running .NET processes available for profiling, discovered from their diagnostic IPC endpoints |
snapshot | Captures a single memory snapshot of a target process |
compare_snapshots | Captures two snapshots with configurable delay and compares them |
analyze | Runs the rule engine against a captured snapshot and returns findings |
get_rules | Lists all available analysis rules with their metadata |
Built-in Rules
| ID | Severity | Category | Description |
|---|---|---|---|
| ML001 | critical | leak | Event handler leak detected |
| ML002 | critical | leak | Static collection growing unbounded |
| ML003 | high | leak | Disposable object not disposed |
| ML004 | high | fragmentation | Large Object Heap fragmentation |
| ML005 | medium | retention | Object retained longer than expected |
| ML006 | medium | allocation | Excessive allocations in hot path |
| ML007 | medium | retention | Closure retaining unexpected references |
| ML008 | low | allocation | Array/list resizing without capacity hint |
| ML009 | low | pattern | Finalizer without Dispose pattern |
| ML010 | low | pattern | String interning opportunity |
Configuration
Create a .memorylens.json file in your project root to customize rule behavior:
{
"rules": {
"ML001": { "enabled": true, "severity": "critical" },
"ML002": { "enabled": true, "severity": "critical" },
"ML003": { "enabled": true, "severity": "high" },
"ML004": { "enabled": true, "severity": "high" },
"ML005": { "enabled": true, "severity": "medium" },
"ML006": { "enabled": true, "severity": "medium" },
"ML007": { "enabled": true, "severity": "medium" },
"ML008": { "enabled": true, "severity": "low" },
"ML009": { "enabled": true, "severity": "low" },
"ML010": { "enabled": true, "severity": "low" }
}
}
Usage Examples
Single Snapshot
Capture a memory snapshot of a running process to inspect current memory state:
> /memorylens
> Take a snapshot of my running API (PID 12345)
Claude will call snapshot with the target PID, then analyze the returned snapshot id and present findings ordered by severity.
Before/After Comparison
Detect memory growth by comparing two snapshots taken with a delay:
> /memorylens
> Check if my app has a memory leak — compare before and after processing 1000 requests
Claude will call compare_snapshots with a delaySeconds value (default 10 seconds) between the two captures, then analyze the diff to identify objects that grew between snapshots.