Let your AI assistant explore SystemVerilog designs — without pasting source code into the chat.
naja-scope is an MCP server that gives AI agents (Claude, and any MCP-compatible assistant) a precise, structured view of your elaborated SystemVerilog design. Instead of dumping thousands of lines of RTL into the model's context, the agent asks targeted questions — what drives this signal? what's inside this module? where does this net come from? — and gets back small, exact answers with file-and-line references.
Built on the najaeda netlist engine.
On a 17-question CVA6 benchmark, the same Claude Code agent scored 17/17 with naja-scope versus 10/17 with grep/read source tools — in 77 turns instead of 123, processing about 5× less input. How it was measured
pip install naja-scope
claude mcp add naja-scope -- naja-scope-mcpSee it in action: demo recording.
Large designs don't fit in a chat window. Pasting RTL is slow, expensive, and the model still can't reliably trace connectivity across hierarchy. naja-scope turns your design into something an agent can navigate:
- 🔎 Trace connectivity — find what drives or loads any signal, across module boundaries.
- 🌲 Walk the hierarchy — explore modules, instances, and ports on demand.
- 🎯 Jump to source — every answer comes with
file:lineranges, so the agent can quote the exact RTL that matters. - 🧩 Logic cones — trace fan-in / fan-out combinational cones up to the register boundary.
- 💡 Recover design intent — enum state names, struct/union fields, and parameter formulas that normally vanish when a design is elaborated.
Works on RTL and gate-level netlists alike — load elaborated SystemVerilog, or a post-synthesis structural Verilog netlist plus its Liberty standard-cell library (see Gate-level designs). VHDL loading is in beta.
All responses are token-bounded: lists paginate, large results truncate with clear markers. Your context stays small; your answers stay accurate.
naja-scope helps most when the answer exists in the elaborated design rather
than in any single source file. In an initial 17-question run on the
cv32a6_imac_sv32 configuration of
CVA6, the same Claude Code agent was
tested with naja-scope and with source-search tools alone.
| Agent setup | Provider and models | Initial automated score | Turns | Input processed | Output tokens |
|---|---|---|---|---|---|
| Agent + naja-scope | Anthropic Claude Code; claude-sonnet-4-6 with claude-haiku-4-5-20251001 helper |
17 / 17 | 77 | 1,058,556 | 19,520 |
| Agent + grep/read source | Anthropic Claude Code; claude-sonnet-4-6 with claude-haiku-4-5-20251001 helper |
10 / 17 | 123 | 5,461,719 | 55,962 |
The difference is clearest on structural questions that source search cannot answer directly:
| CVA6 question | Agent + naja-scope | Agent + grep/read source |
|---|---|---|
Flattened register groups under ex_stage_i |
92, in 4 turns | No answer at the turn limit |
Flattened register groups under commit_stage_i |
0, in 3 turns | No answer at the turn limit |
Elaborated hpdcache_mux variants |
20, in 3 turns | No answer at the turn limit |
Source search remains the right tool for local textual questions. naja-scope adds the elaborated hierarchy, connectivity, lowered primitives, and generated or uniquified structures that are otherwise difficult to reconstruct.
See the benchmark methodology and multi-model runner and historical result record for configuration, scoring, token accounting, and reproducibility details.
pip install naja-scopeThat's it — najaeda and the MCP runtime come along automatically.
claude mcp add naja-scope -- naja-scope-mcpOr add it to any MCP client's config:
{
"mcpServers": {
"naja-scope": {
"command": "naja-scope-mcp"
}
}
}Then just ask your assistant to load a design and start exploring:
"Load my UART design from
rtl/uart.svwith topuart_top, then show me everything that drivestx_o."
The agent loads the design once and answers follow-up questions instantly — no re-reading source, no giant pastes.
ChatGPT connects to MCP servers over an HTTP endpoint (custom connectors / Developer mode), so run naja-scope as an HTTP server instead of stdio:
naja-scope-mcp --transport streamable-http --host 127.0.0.1 --port 8000This serves MCP at http://<host>:8000/mcp. Expose that URL where ChatGPT can
reach it (e.g. an ngrok/cloudflared tunnel for a local run), then in ChatGPT
open Settings → Connectors, add a custom connector, and paste the URL
(https://<your-host>/mcp). The HTTP server has no built-in auth — only expose
it over a trusted tunnel.
Already synthesized? Load the structural Verilog netlist together with the Liberty library that defines its standard cells, and navigate the gates the same way as RTL:
"Load the Liberty library
pdk/stdcells.lib, then the gate netlistbuild/top.v, and tell me what cellstopis built from and what drivesdata_out."
Hierarchy, per-cell counts, drivers/loads, and logic cones all work on the
netlist; cones stop at the sequential cells. get_source shows an object's
line in the netlist, and for Yosys output yosys_source_attributes=True adds
origins that get_source(path, origin=0) reads back in the RTL.
VHDL loading is available in beta. Call
load_vhdl(file=["pkg.vhd", "child.vhd", "top.vhd"], top="my_entity") to
explore its elaborated hierarchy and connectivity; the files may be listed in
any order. A single path per call also works (load packages first);
package-only files may return top: null until the top file is loaded. The frontend supports a restricted two-state RTL subset,
and supported constructs may change. get_intent/load_intent remain
SystemVerilog-only; VHDL source ranges are not guaranteed.
Once a design is loaded, your assistant can:
- Resolve any signal or instance by hierarchical path (with glob and did-you-mean suggestions).
- Find objects design-wide by pattern.
- Show the hierarchy of any module.
- Get drivers / loads of a net — the real endpoints, across hierarchy;
literal drivers preserve four-state
0/1/X/Zvalues. - Trace logic cones (fan-in / fan-out) and see the register frontier.
- Get source — the exact SystemVerilog lines behind any object.
- Get a module card — ports, counts, clock/reset at a glance.
- Recover design intent — state-machine names, struct fields, parameter expressions lost during elaboration.
- Python 3.10+
- Works anywhere
najaedaruns (Linux, macOS, Windows)
- 🐛 Found a bug or have a feature request? Open an issue on GitHub →
- 📫 Get in touch: contact@keplertech.io
Apache-2.0. See LICENSE.
Requires naja-schematic 0.2.0 or later (the release containing the embeddable viewer API):
pip install "naja-scope[schematic]"Restart the MCP server after installation. Load a design as usual, then use:
open_schematic(path="top.u_cpu"): returns a local browser URL and focuses the instance. Omitpathfor the top. Anonymous#idinstances are supported.annotate_schematic(items=[{"path": "top.u_cpu", "message": "Check reset", "severity": "warning"}]): replaces the overlay. Usekind="term"with a pin/port path to annotate that terminal; annotations apply to the whole port, not individual bus bits. Passitems=[]to clear. At most 200 annotations, each with at most 2000 message characters.get_schematic_selection(): returns the last clicked instance as a regular naja-scope path, usable with source, hierarchy and module-card queries.
The viewer shares the existing raw naja universe; it does not elaborate again. The server binds to loopback and returns a token-bearing URL. Open that URL on the machine running the MCP server; it is not a remote or embedded MCP UI. Treat the URL as access to the loaded design. Design loads/resets refresh open viewers and clear selection, focus and annotations. The browser server stops with naja-scope. Existing tools remain usable without the schematic extra.