MsgPack (LsMsgPack)

io.github.mlsomersv2026.10.10.2更新于 Oct 10, 2026

Decodes MsgPack (LsMsgPack schemas, type ids) as text and reads it from variables while debugging.

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概览

AI 生成的概览

将 MsgPack 二进制数据解码为可读的 JSON，并可读取在 VS Code 或 Visual Studio 调试器中暂停的程序的字节变量。

功能
该服务器把 MsgPack 数据转换为带注释的 JSON，并解析 LsMsgPack 索引式架构，使类型和属性编号变为名称。工具可从十六进制、base64、字节值、文件或先前解码的文档中解码数据；列出调试会话和暂停栈帧的变量；读取并解码暂停程序中某个表达式的字节；解释指定偏移处字节的含义；搜索文本或值；以及把数据读入已编译 .NET 程序集的类并报告不匹配之处。解码后的数据会获得文档编号，便于后续调用，输出可按路径、字节范围、视图和偏移选项进行筛选。
适用场景
当助手需要检查难以用十六进制或 base64 阅读的 MsgPack 数据时很有用，尤其是架构仅以 16 字节编号引用的 LsMsgPack 数据。也适用于在 VS Code 或 Visual Studio 中调试 .NET 程序，助手可以读取暂停栈帧中变量或成员的字节并解码。
运行要求
需要 .NET 运行时 8 或更高版本；以全局工具 LsMsgPack.Mcp 安装，命令为 lsmsgpack-mcp，通过 stdio 在本地运行。调试功能需要 VS Code 的 MsgPack Explorer 扩展或 Visual Studio 的 MsgPack Debugger Extension，它们监听 127.0.0.1，并在用户配置目录下写入包含端口和令牌的锁文件。未声明任何账户、API 密钥或环境变量。
安装前请注意
调试读取会接触正在暂停的进程：默认只读取变量和成员路径，但 IDE 设置可允许任意表达式，读取不可定位的流会将其消耗掉，且 IDE 会先询问用户。read-as-class 工具会在单独进程中加载 .NET 程序集并运行该类的构造函数和 setter，因此只应使用可信的程序集。saveTo 选项会把解码后的字节写入文件。

安装

在 SourceWeft 中

  1. 打开 控制台中的 MsgPack (LsMsgPack)，将其添加到工作区。
  2. 为需要使用其工具的对话启用该服务。

Desktop only，通过 STDIO。 STDIO 服务会启动本地进程，因此需要 SourceWeft 桌面宿主。

其他 MCP 客户端

参照 仓库 中的启动说明。

README

LsMsgPack MCP server

MsgPack for AI agents. An MCP server and a command line tool that decode MsgPack data into text an AI (or a person in a terminal) can read, and that read the bytes of a variable of a program paused in the debugger of VS Code or Visual Studio.

Language models read text, not bytes. Hex or base64 costs several tokens per byte, and decoding it by hand is slow and error-prone. Some data can't be decoded from the bytes at all: LsMsgPack's indexed schema writes property names as indexes, and a schema reference holds only the 16-byte id of the schema. This tool decodes the data with the LsMsgPack library itself (the code of MsgPack Explorer) and writes it as JSON with comments:

text
MsgPack "doc1" 247 bytes from payload (byte[], Launch Api).Structure: indexed schema (inline, 3 types) followed by the bodyNo errors, 0 warnings or comments.Schema (inline): type ids and property ids in the body are indexes into these lists.  #0 Invoice: Id, Customer, Billing, Lines, Date, Reference, Tags  #1 Address: Street, Number, City  #2 Line: Product, Quantity, Price
Objects (JSON with // comments: a type name comes from a type id, a name with ~ is inferred from the schema; dictionary keys that are not strings are not quoted):{ // Invoice~  "Id": 1234,  "Customer": "Alice",  "Billing": { "Street": "Main street", "Number": 12, "City": "Amsterdam" }, // Address~  "Lines": [ // 2 items    { "Product": "Apples", "Quantity": 3, "Price": 1.25 }, // Line~, Price: decimal    { "Product": "Pears", "Quantity": 2, "Price": 0.99 } // Line~, Price: decimal  ],  "Date": "2026-10-05T12:30:00Z", // timestamp  "Reference": "5bad8f0fcbd99f46a16570867728950e", // bin, 16 bytes, as Guid 0f8fad5b-d9cb-469f-a165-70867728950e  "Tags": ["fruit", "fresh"] // 2 items}

It reads any MsgPack, not only data written by LsMsgPack. Errors come with their offset, and the values read after an error are marked.

Install

Requires the .NET runtime 8 or later.

bash
dotnet tool install -g LsMsgPack.Mcp      # the command is lsmsgpack-mcp

From source: dotnet publish LsMsgPackMcpServer -c Release -o <folder>, then run dotnet <folder>/LsMsgPackMcp.dll in place of lsmsgpack-mcp.

Add it to your agent

ClientHow
VS Code (Copilot agent mode)Nothing to do with the MsgPack Explorer extension: it registers the server "MsgPack (LsMsgPack)".
Claude Codeclaude mcp add lsmsgpack -- lsmsgpack-mcp
Visual Studio 2022 (17.14+)%USERPROFILE%\.mcp.json (or .mcp.json next to the solution): { "servers": { "lsmsgpack": { "type": "stdio", "command": "lsmsgpack-mcp" } } }
Claude Desktop, Cursor, Windsurf...{ "mcpServers": { "lsmsgpack": { "command": "lsmsgpack-mcp" } } }

In VS Code, MsgPack: Copy MCP Server Configuration... copies these: for the tool when it is installed, otherwise for the server that comes with the extension (its path has the extension's version in it, so copy it again after an update).

Tools

ToolWhat it does
msgpack_debug_statusThe IDEs with the MsgPack extension, their debug sessions, and where the program is paused.
msgpack_debug_localsThe variables of the paused stack frame with their types. The ones that can hold bytes are marked.
msgpack_debug_readReads the bytes of an expression in the paused program and decodes them. Reads byte[], streams (seekable ones go back to their position), Memory<byte>, List<byte>, HttpContent and base64 or hex strings. In VS Code also JavaScript Uint8Array/Buffer and Python bytes. schemaStore reads the schema from the program's SchemaStore when the payload refers to one. saveTo also writes the bytes to a file.
msgpack_decodeDecodes data (hex, base64 or byte values), a file, or a doc decoded before. schemas takes a SchemaStore.Export (or one schema) for schema references.
msgpack_read_as_classReads the data into a class of a compiled .NET assembly (assembly: the .dll of the build output, type: the class) and reports what doesn't match: properties the class doesn't have (with "did you mean"), values that don't convert, classes without a schema entry, type ids that aren't found, with the paths of the objects (reporting differences). Also shows the object that was read. The assembly is loaded in a separate process: it runs the class's constructors and setters.
msgpack_explain_offsetWhat the byte at an offset is: the items holding it, the object member, the header and content bytes, and the bytes around it.
msgpack_searchThe items holding a text or a value, with offsets and object paths.

Every decoded payload gets a document id (doc1, doc2...) for follow-up calls. The output can be narrowed and switched with these options:

  • view: objects (default), items (the MsgPack encodings with offsets) or both.
  • path (e.g. Lines[2]), from/to (a byte range), maxNodes, maxString.
  • offsets adds the offset of every value. issues takes errors, all or none.
  • endian and continueOnError (on by default).

Debugging

The MsgPack extensions of VS Code (MsgPack Explorer) and Visual Studio (MsgPack Debugger Extension) listen on 127.0.0.1. They write a lock file with their port and a random token to ~/.lsmsgpack/ide (%USERPROFILE%\.lsmsgpack\ide). The MCP server uses the IDE that started it, otherwise the one whose workspace holds its working directory (ide picks one when several run).

  • By default only variable and member paths are read (buffer, this._payload, response.Content, items[2].Data), no method calls. The IDE setting can allow any expression: lsmsgpack.mcp.allowAnyExpression in VS Code (user settings only), Tools > Options > MsgPack Explorer in Visual Studio.
  • A stream that can't seek is consumed by reading it, so the IDE asks the user first.
  • The IDE settings can turn the bridge off: lsmsgpack.mcp.enabled in VS Code, and the same options page in Visual Studio.

Command line

bash
lsmsgpack-mcp decode payload.msgpack                # the objectslsmsgpack-mcp decode payload.msgpack --view items   # the items with offsets and encodingslsmsgpack-mcp decode --data "82 a4 4e 61 6d 65 ..." # bytes as textlsmsgpack-mcp explain payload.msgpack 0x7b          # what the byte at 0x7b islsmsgpack-mcp search payload.msgpack Amsterdamlsmsgpack-mcp read-as payload.msgpack --assembly bin/Debug/net8.0/MyApp.dll --type Order   # what doesn't match the classlsmsgpack-mcp debug status | debug locals | debug read <expression>

lsmsgpack-mcp --help lists the options. Without arguments it runs the MCP server on stdin/stdout.

More: docs/Mcp.md.

来源：LsMsgPackMcpServer/README.md，提交 7be5fc8

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版本历史

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  1. v2026.10.10.2最新Oct 10, 2026