pyslang-mcp

pyslang-mcp is a local Model Context Protocol server that gives AI agents compiler-backed, read-only context for Verilog and SystemVerilog projects.

It wraps pyslang so an MCP client can ask questions against parsed and elaborated HDL instead of plain text:

• What modules, interfaces, and packages are in this filelist?
• What diagnostics does the compiler frontend report?
• What is the instance hierarchy below this top?
• Where is this symbol declared or referenced?
• Did my include paths, defines, and nested .f files resolve as expected?

This is not a simulator, synthesizer, waveform viewer, linter replacement, or RTL refactoring tool. It is a small semantic analysis service for local HDL checkouts.

That read-only boundary is intentional. It keeps the server side-effect free, reduces the blast radius in IP-protected workspaces, and makes it safer to use in local and CI environments.

It was decided to keep pyslang-mcp read-only. The LLM handles the actual RTL coding, while pyslang-mcp serves as the compile/elab-backed reader, checker, and explainer for code that already exists. In other words, the model drafts the RTL and the MCP server verifies what the compiler frontend sees.

[!NOTE] The project is currently early-stage and published on PyPI and the MCP Registry for local stdio use.

Why ASIC And EDA Engineers Might Care

Most AI coding tools are good at searching text. HDL usually needs more than that.

In real projects, useful answers often depend on filelists, packages, includes, defines, generate blocks, and hierarchy. pyslang-mcp gives an agent a compact compiler-backed view of that structure, while keeping the server read-only and scoped to a project root you provide.

Good fits:

• triaging parse and semantic diagnostics before asking an agent to reason about RTL
• checking what a .f file expands to
• listing design units in a block or small IP
• finding a declaration without chasing comments and stale grep hits
• getting hierarchy and port-connection context for review/debug prompts
• giving workflow agents HDL context without handing them an EDA runtime

Quickstart

Install the package:

pip install pyslang-mcp

Run the local stdio server:

pyslang-mcp

For contributor setup, clone the repo and install it in editable mode:

git clone https://github.com/ariklapid/pyslang-mcp.git
cd pyslang-mcp
python -m venv .venv
./.venv/bin/pip install -e '.[dev]'

Run the checkout stdio server:

./.venv/bin/python -m pyslang_mcp

The installed console script works too:

./.venv/bin/pyslang-mcp

Run tests:

./.venv/bin/pytest

MCP Client Config

Use local stdio. The MCP client should launch the server on the same machine, VM, or dev container that can see your RTL checkout.

{
  "mcpServers": {
    "pyslang-mcp": {
      "command": "pyslang-mcp",
      "args": []
    }
  }
}

For editable checkout installs, point the command at the checkout virtual environment instead:

{
  "mcpServers": {
    "pyslang-mcp": {
      "command": "/absolute/path/to/pyslang-mcp/.venv/bin/python",
      "args": ["-m", "pyslang_mcp"]
    }
  }
}

Tool calls must provide a project_root. Source paths, filelists, and include directories may be absolute or relative, but

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