cg-agent-kit - an MCP server for FPGA design in C⏚

ci License: MIT

Give an AI agent the ability to design real hardware. cg-agent-kit is a Model Context Protocol server that drives the open-source C⏚ Verilog compiler - so an agent writes a C-like HDL, and the server compiles, checks, generates Verilog, and synthesis-checks it against the real toolchain instead of hallucinating Verilog that doesn't build.

C⏚ ("C-Ground") is a hardware description language with C-like syntax that compiles to clean, standard Verilog. The compiler is open source at github.com/Neosyn-Logic/cg-compiler.

Tools

Tool	What it does
cg_check	Compile + validate C⏚; structured diagnostics (file:line, the fix)
cg_generate_verilog	Emit synthesizable Verilog
cg_simulate	Simulate a design (iverilog backend, or the commercial fast sim)
cg_synth	Yosys-synthesize the Verilog: REAL / FOLDED / SUSPECT verdict + cell count
cg_example	Scored lookup into a curated, validated-code dictionary (18 entries)
cg_suggest_for_error	Map a compiler error to the recipe with the fix pattern
cg_fsm / cg_graph	A task's compiled state machine / a network's graph
cg_docs	C⏚ language + patterns reference

The kit's organizing idea: agents seed-and-adapt from validated code and verify against the real compiler at every step - not invent-from-scratch.

Open vs commercial

This kit and the compiler it drives are open. The fast (bytecode) cycle-accurate simulator is part of the commercial Neosyn SDK - so cg_simulate's default bytecode backend asks you to upgrade, while the iverilog backend works fully (generate Verilog + run Icarus Verilog). Everything else - check, generate, synth, the dictionary, docs - runs entirely on the open compiler. More at neosyn.io/open.

Install

pip install cg-agent-kit

Then point it at a built C⏚ compiler jar (download the prebuilt jar from cg-compiler releases, or build from source):

export CG_JAR=/path/to/cg-language-server.jar

(Optional, for cg_synth and the iverilog sim backend, install yosys and iverilog.)

Run

As an MCP server (for Claude Desktop, Cursor, Windsurf, or any MCP client):

cg-mcp-server

Add it to your MCP client config, e.g.:

{
  "mcpServers": {
    "cg": { "command": "cg-mcp-server", "env": { "CG_JAR": "/path/to/cg-language-server.jar" } }
  }
}

Or call the verification functions directly from Python:

from cg_agent_kit import cg_mcp_server as cg
print(cg.check(open("Counter.cg").read()))
print(cg.generate(open("Counter.cg").read()))

The kit bundles 18 validated C⏚ designs and the language + CPU-pattern references the cg_docs tool serves.

License

MIT - see LICENSE. C⏚ began as the Synflow Cx toolchain.