Configuration

mcilspy follows a zero-configuration philosophy — it works out of the box with sensible defaults. The configuration surface is intentionally small: one environment variable for logging and the standard MCP client configuration for connecting to the server.

MCP Client Configuration

Claude Code

The simplest setup. One command registers mcilspy as an MCP server:

claude mcp add ilspy -- mcilspy

For development against a local checkout:

claude mcp add ilspy -- uv run --directory /path/to/mcilspy mcilspy

Claude Desktop

Add to your claude_desktop_config.json (typically at ~/Library/Application Support/Claude/claude_desktop_config.json on macOS or %APPDATA%\Claude\claude_desktop_config.json on Windows):

{
  "mcpServers": {
    "ilspy": {
      "command": "mcilspy"
    }
  }
}

To enable debug logging:

{
  "mcpServers": {
    "ilspy": {
      "command": "mcilspy",
      "env": {
        "LOGLEVEL": "DEBUG"
      }
    }
  }
}

Generic MCP Client

mcilspy communicates over stdin/stdout using JSON-RPC. Point any MCP-compatible client at the mcilspy command:

{
  "command": "mcilspy",
  "args": [],
  "transport": "stdio"
}

If installed via uvx, use:

{
  "command": "uvx",
  "args": ["mcilspy"],
  "transport": "stdio"
}

Environment Variables

mcilspy reads one environment variable:

Variable	Default	Values	Purpose
LOGLEVEL	INFO	DEBUG, INFO, WARNING, ERROR	Controls log verbosity on stderr

Logs are written to stderr exclusively — stdout is reserved for the MCP JSON-RPC protocol. You will never see log output mixed into tool responses.

Debug Mode

Set LOGLEVEL=DEBUG to see detailed information about tool invocations, subprocess commands, and metadata parsing:

LOGLEVEL=DEBUG mcilspy

In Claude Code, you can set environment variables in the MCP configuration:

claude mcp add ilspy -e LOGLEVEL=DEBUG -- mcilspy

Debug output includes:

• Every ilspycmd subprocess command and its arguments
• Metadata reader operations and timing
• Search pattern compilation and match counts
• Output truncation decisions and temp file paths

Tip

Debug logs are useful for reporting issues. If a tool returns unexpected results, re-run with LOGLEVEL=DEBUG and include the stderr output in your bug report.

Development Setup

For working on mcilspy itself, install in development mode and run directly:

git clone https://git.supported.systems/MCP/mcilspy.git
cd mcilspy
uv pip install -e .
mcilspy

Or run without installing:

uv run --directory /path/to/mcilspy mcilspy

To test with Claude Code using a local development copy:

claude mcp add ilspy-dev -- uv run --directory /path/to/mcilspy mcilspy

This registers a separate ilspy-dev server alongside any production installation, so you can compare behavior between versions.

Tool Defaults

These defaults are built into mcilspy and cannot be changed via configuration. They can be overridden per tool call:

Parameter	Default	Tool
max_output_chars	100,000	decompile_assembly
max_results	100	search_strings
max_results	1,000	search_methods, search_fields, list_types, search_types
language_version	Latest	decompile_assembly, decompile_method
show_il_code	false	decompile_assembly
show_il_code	true	decompile_method