Rbinilspy

rbinilspy

[](LICENSE) [](rust-toolchain.toml) [](https://dotnet.microsoft.com)

MCP server for ILSpy-based .NET assembly analysis.

rbinilspy manages persistent ILSpy sessions with an in-memory C# worker process, loads .NET assemblies for analysis, and exposes 17 tools as named Model Context Protocol tools over stdio.

Tools

Session Management

• dn_open / dn_close / dn_sessions -- open/close/list persistent ILSpy sessions
• dn_metadata -- assembly metadata: types count, namespaces count

Discovery & Navigation

• dn_namespaces -- list namespaces with type counts, filter, and pagination
• dn_types -- list types with name/namespace filter and pagination
• dn_search -- search types or cached member names by substring
• dn_type_info -- type metadata: base types, interfaces, attributes, modifiers

Decompilation

• dn_decompile -- full type decompilation to C# (with result caching)
• dn_decompile_method -- decompile a single method (token-efficient, no full type dump)
• dn_members -- list methods/properties/fields (with result caching)
• dn_il -- raw CIL disassembly
• dn_search_source -- grep decompiled C# source for a pattern

Assembly Analysis

• dn_references -- external assembly dependencies
• dn_usages -- find usages of a pattern across decompiled types
• dn_resources -- list embedded resources
• dn_raw_cmd -- passthrough for arbitrary ilspycmd invocations

Requirements

• .NET 10 SDK (for worker build)
• ILSpy CLI -- dotnet tool install -g ilspycmd
• Rust stable toolchain (for building the MCP server)

Quick Start

# Build the C# worker
cd ilspy-worker && dotnet publish -c Release -o bin/publish

# Build and run the MCP server
cd .. && cargo build --workspace
RBM_CACHE_DIR=./cache cargo run -p rbm-server

The server speaks the MCP protocol over stdio. Configure your MCP client:

{
  "mcpServers": {
    "rbinilspy": {
      "command": "/path/to/rbinilspy/target/debug/rbinilspy",
      "args": []
    }
  }
}

Configuration

| Variable | Default | Description | | --- | --- | --- | | RBM_CACHE_DIR | ./rbinilspy-cache | Cache root | | RBM_TOOL_TIMEOUT_SECS | 30 | Per-tool timeout (seconds) | | RBM_ILSPY_WORKER | auto‑detected | Path to the C# worker (binary or project dir) | | RBM_ILSPY_CMD | ilspycmd | Path to the ILSpy CLI executable | | RBM_ILSPY_CMD_TIMEOUT_MS | 60000 | ilspycmd subprocess timeout (milliseconds) |

Architecture

MCP Client
  -> stdio JSON-RPC
  -> rbinilspy server (Rust)
  -> C# worker process (stdin/stdout JSON-RPC)
  -> ilspycmd subprocess (per-decompilation)

Assemblies are opened once and cached in the C# worker's memory. Decompiled output and member listings are cached per type for the session lifetime.

Project Structure

crates/
  rbm-core/      Cache paths, config, error types
  rbm-server/    MCP server binary (rbinilspy)
ilspy-worker/    C# persistent worker for ilspycmd

License

MIT -- see [LICENSE](LICENSE).

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: kirkderp
• Source: kirkderp/rbinilspy
• License: MIT

Install and usage instructions live in the source repository linked above.