Compiler Explorer

What it does

Compiler Explorer (godbolt.org) has an MCP endpoint built into the site itself, so an assistant can do what a person does in the web UI: pick a language and compiler, compile a snippet with chosen flags and libraries, read the generated assembly, and optionally run the program. It can also explain an assembly mnemonic for a given instruction set, turn a session into a godbolt.org/z/ short link, and load an existing short link back into source and compiler settings so it can be compiled again.

There is nothing to install: the public endpoint at https://godbolt.org/mcp speaks stateless Streamable HTTP and asks for no sign-in. Anyone running their own Compiler Explorer instance gets the same endpoint at <host>/mcp, using the compilers configured on that instance.

Seven tools are registered in lib/mcp/index.ts. list_compilers returns full details for 25 compilers by default (DEFAULT_MAX_RESULTS in lib/mcp/tools/compilers.ts); past that cap it falls back to id and name only unless maxResults is raised, and its latestPerMajor option narrows the list to the newest stable release per major version.

What it needs

For the public endpoint: an MCP client that supports remote Streamable HTTP servers and network access to godbolt.org. No account or key. To self-host: a Compiler Explorer checkout run with make on Linux, Node.js at the version pinned in .node-version or newer, and the compilers you want configured; the endpoint is then at <your-host>/mcp.

Limits

Output from compile is capped by line count by default: 500 lines of assembly, 100 of stdout and 100 of stderr; raise maxAsmLines, maxStdoutLines or maxStderrLines for more. Only POST is accepted; GET and DELETE return 405, and there are no sessions. Shortlinks with several panes (executors, conformance views, CMake projects) are flattened to basic compile inputs by get_shortlink_info. The public site's compilers and execution sandbox are what the hosted endpoint offers; code runs on Compiler Explorer's servers, not yours.

Who it suits

Suits developers who want an assistant to check what a compiler generates, compare flags or compiler versions, test a small program across toolchains, or share a reproducible godbolt.org link, without installing compilers locally. Because the hosted endpoint needs no sign-in, it fits quick setup in any client that takes a remote URL. It works on snippets, not on a local project: it cannot read your files or build with your own toolchain, so for whole-repo builds use local tools instead. Teams that cannot send source to a public service can run their own Compiler Explorer and point clients at its /mcp.