time-mcp

<div align="center"> <h1>time-mcp</h1> <p><strong>A tiny UTC clock for MCP.</strong><br />Written in assembly. Launched over <code>stdio</code>.</p> <p><strong>697 bytes</strong> &nbsp;·&nbsp; Current Linux x86 ELF32 build</p> <p><em>Smaller is the goal.</em></p> </div>

Tiny binaries, real utility: time-mcp is a Model Context Protocol (MCP) server that returns the current UTC timestamp. The client launches it directly over stdio.

One call, one timestamp

sequenceDiagram
    participant Client as MCP client
    participant Server as time-mcp
    Note over Client,Server: JSON-RPC over stdio
    Client->>Server: tools/call<br/>name = date<br/>arguments = {}
    Server->>Server: Read current UTC clock
    Server-->>Client: JSON-RPC result<br/>content[0].type = text<br/>content[0].text = YYYY-MM-DD HH:MM:SS UTC (DDD)

The server handles MCP initialization and tool discovery, then exposes one no-argument tool, date. Call it with {}. It returns text in this format:

YYYY-MM-DD HH:MM:SS UTC (DDD)

Get running

Build the native target for your machine:

make

Connect it from MCP Inspector or MCPJam Inspector using STDIO, the absolute path to the executable, and no arguments. Then list tools and run date with {}.

| Setting | Value | | :-------- | :-------------------------------------------------- | | Transport | STDIO | | Command | Absolute path, such as /path/to/time-mcp/time-mcp | | Arguments | None |

On macOS Apple Silicon, make also builds Linux ELF32 when NASM is installed. On Linux x86/x86_64, it builds the Linux target. Linux requires a kernel with 32-bit x86 support; native macOS Intel and Linux ARM builds are not provided.

Test it

The C regression harness exercises the assembly server over stdio. Install the test-only compiler, pkg-config, and json-c dependencies described in CONTRIBUTING.md, then run the test for your platform:

make test-macos
# or, on Linux x86/x86_64
make test-linux

Under the hood

| Target | Implementation | | :-------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | Linux | Hand-crafted x86 ELF32 executable with an overlapped header; no libraries or dynamic linker; four kernel syscalls: sys_read, sys_time, sys_write, sys_exit. | | macOS | Native Apple Silicon arm64 assembly using XNU syscalls and Apple's standard linker. |

These are separate native executables, not a universal binary. File lengths are measured with wc -c and can be reproduced with make size. The macOS file includes Mach-O alignment and an ad-hoc code signature, so its total size is not a measure of the assembly code alone. The production executables have no library dependencies.