MachOKitMCP

MachOKit MCP Server

machokit-mcp is an MCP server that exposes MachOKit to LLM-driven agents (Claude Code, Claude Desktop, etc.) over stdio. It is implemented in Swift on top of the official MCP Swift SDK.

Build

swift build -c release

The product is an executable named machokit-mcp. Its absolute path is MachOKitMCP/.build/release/machokit-mcp after the release build.

Platforms: macOS 13+. The package itself builds on Linux too, but every loaded-image tool returns an error there because the underlying _dyld_* APIs are Darwin-only. File- and cache-based tools work cross-platform.

Register with Claude Code

Add an entry to ~/.config/claude/mcp.json (or to a project-level MCP config). Use the absolute path to the binary:

{
  "mcpServers": {
    "machokit": {
      "command": "/absolute/path/to/MachOKitMCP/.build/release/machokit-mcp"
    }
  }
}

Restart Claude Code. The server should appear and expose the tools listed below.

Tools

All tools accept a format argument with values "json" (default, compact JSON) or "text" (pretty-printed JSON). List-returning tools accept limit and offset for pagination.

Tools that inspect a single Mach-O accept a target chosen via:

• path — absolute file path. For fat / universal binaries add arch

(e.g. "arm64", "x86_64", "arm64e").

• image_name — Darwin only; matches dyld's substring lookup against

loaded images.

• image_index — Darwin only; 0-based index into the current process's

loaded images.

Mach-O — basic

| Tool | Purpose | | --------------------- | ------------------------------------------------- | | macho_info | One-shot summary (header + flags + UUID + deps) | | macho_header | Header fields only | | macho_load_commands | LC list with type, size, offset, summary, and detailed payload fields | | macho_segments | Segments and their sections | | macho_dependencies | LCLOADDYLIB / LCREEXPORT / weak / lazy / upward | | macho_rpaths | LCRPATH entries | | macho_uuid | LCUUID | | macho_version | LCSOURCEVERSION / LCVERSIONMIN* / LCBUILDVERSION / LC_MAIN | | macho_info_plist | Embedded __TEXT,__info_plist |

Mach-O — symbols & strings

| Tool | Purpose | | ------------------------- | ---------------------------------------------------- | | macho_symbols | Symbol table entries (paginated) | | macho_indirect_symbols | Indirect symbol table | | macho_strings | C strings from string-literal sections | | macho_ustrings | UTF-16 strings from __ustring | | macho_cfstrings | __cfstring entries with resolved string contents | | macho_exports | Export trie | | macho_imports | Deduplicated import list (combines bind/lazy/weak) | | macho_bindings | Raw bind / lazy / weak / classic / classic-lazy lists | | macho_rebases | Rebase operations expanded | | macho_lookup_symbol | Find a symbol by name (mangled or demangled) |

Mach-O — advanced

| Tool | Purpose | | ----------------------------- | --------------------------------------------- | | macho_function_starts | LCFUNCTIONSTARTS expansion | | macho_code_signature | Code directories, entitlements (as JSON) | | macho_dyld_chained_fixups | Chained fixup header, segments, imports | | macho_relocations | External relocations |

Fat / universal

| Tool | Purpose | | ------------- | --------------------------------------------- | | fat_inspect | Architectures in a fat binary (cputype, offset, size, align) |

Dyld shared cache

These tools take a path to a cache file. include_subcaches widens the view to a FullDyldCache for tools that support it.

| Tool | Purpose | | ----------------------- | ----------------------------------------------- | | dyld_cache_info | Header (uuid, type, platform, OS, image count) | | dyld_cache_mappings | Mapping table | | dyld_cache_images | List of images in the cache (path, address) | | dyld_cache_subcaches | Subcache table | | dyld_cache_image_info | Open a single image (by image_path) as a Mach-O |

Loaded process (Darwin only)

| Tool | Purpose | | -------------------------- | ---------------------------------------- | | loaded_images_list | Iterate _dyld_image_count images | | loaded_image_info | Full summary for one loaded image | | loaded_dyld_cache_info | Mapped shared cache for current process |

Manual smoke test (no MCP client)

The stdio transport speaks newline-delimited JSON-RPC. After the standard initialize handshake you can call any tool:

(
  printf '%s\n' \
    '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"smoke","version":"0"}}}' \
    '{"jsonrpc":"2.0","method":"notifications/initialized"}' \
    '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"macho_info","arguments":{"path":"/bin/ls","arch":"arm64","format":"text"}}}'
  sleep 2
) | ./.build/release/machokit-mcp

Output format notes

Currently, both format=json and format=text return JSON; the only difference is whether it is compact or pretty-printed. Field labels mirror C constants (e.g. MH_EXECUTE, LC_SEGMENT_64, S_REGULAR, CPU_TYPE_ARM64) so that the data is directly cross-referenceable with Apple's open-source headers.

Release

Release commits should update the Swift server version before tagging:

scripts/release.sh 0.3.0

The script requires a clean working tree, updates Sources/MachOKitMCP/Version.swift, runs build verification, commits the version bump, and creates an annotated tag with the same bare SemVer string.

macho_load_commands keeps the compact top-level fields (type, size, offset, summary) and adds fields for command-specific payload values. Where MachOKit exposes decoded values, the tool prefers those decoded values and includes the underlying integer value in parentheses for enums and bitsets where unknown values matter. Segment protections and flags are expanded to constant names, dylib/runpath/dylinker strings are extracted, platforms/tools/thread flavors are enum-decoded, version fields include components, and linkedit/dyld ranges include computed end offsets.

Limitations

• Read-only. No writeback to binaries, no cache extraction to disk.
• File-based tools require an absolute path. Symlinks are followed by the

underlying file APIs.

• loaded_* tools only work in the server's own process — they cannot

introspect another running process.

• The MachOImage enumeration depends on _dyld_*, so on Linux these

tools always error out.

Source & license

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

• Author: swiftbin
• Source: swiftbin/MachOKitMCP
• License: MIT

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