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.

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

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

# 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": []
    }
  }
}

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.

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

MIT -- see LICENSE.