ByteAsk Embedded MCP is the open-source server behind ByteAsk Embedded Docs: a source-grounded, page-cited evidence-retrieval MCP server for coding agents (Claude Code, Codex, Cursor) that write firmware / driver / protocol code and need exact facts — SunSpec points, register offsets, Modbus function codes, trip thresholds, SCPI commands, API symbols.

It returns verbatim snippets with page citations — never an authored answer — and when nothing is relevant enough it says no match rather than fabricate. Every document is treated equally: no authority layer, no filters.

Why

• Cited, or nothing. Every hit is verbatim source text with a section + page citation. On a miss it returns an honest "no confident match" — it never invents a register value.
• Built for coding agents. The tool descriptions and triggers are tuned so agents call search_docs reflexively the moment they see a hex literal, a Modbus code, an IEEE clause, a SCPI verb, or an MCU part number — before answering from memory.
• Two transports, one server. stdio for local agents, Streamable HTTP for hosted.
• Bring your own retrieval. The search engine is a two-method interface — swap in anything behind BYTEASK_BACKEND without touching the server.
• Zero-setup demo. The bundled SampleBackend runs immediately. No API keys.

Quickstart

Requires Python ≥ 3.10 and uv.

uv sync
uv run byteask-embedded-mcp        # run as an MCP server (stdio)

That's it — the bundled SampleBackend serves a couple of illustrative records, so search_docs works immediately. Run the offline tests with uv run pytest.

Connect a client

Hosted (no install)

The hosted server speaks Streamable HTTP at https://mcp.byteask.ai/mcp and is backed by the full licensed corpus.

Claude Code:

claude mcp add --transport http byteask-embedded-docs https://mcp.byteask.ai/mcp

{
  "mcpServers": {
    "byteask-embedded-docs": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://mcp.byteask.ai/mcp"]
    }
  }
}

Local (this repo)

The project-scoped .mcp.json registers the stdio server for clients that read it. Manually, for Claude Code:

claude mcp add byteask-embedded-docs -- uv run byteask-embedded-mcp

Tools

Input is natural language (or an exact identifier). Output is compact markdown.

Example output:

## Results for "what Modbus function code writes multiple registers"

### Sample — Modbus Application Protocol (illustrative) — §6.12, p.30
> Function code 16 (0x10), Write Multiple Registers, writes a block of contiguous
> holding registers (1 to 123 registers) in a remote device. ...
_ref: sample:modbus-fc16_

Plug in your own retrieval

The server depends only on a two-method interface (backend.py):

class SearchBackend(Protocol):
    def search(self, query, limit=8, effort=None) -> dict: ...
    def get_context(self, result_id, effort=None) -> dict: ...

Implement it, expose a factory make_backend(config) -> SearchBackend, and point the server at it:

BYTEASK_BACKEND="my_pkg.my_module:make_backend"

The exact return-value contracts are documented at the top of backend.py.

Configuration

All settings are environment variables (loaded from .env; see .env.example).

MCP_TRANSPORT=http MCP_HTTP_AUTH_TOKEN=$(openssl rand -hex 32) \
  uv run byteask-embedded-mcp --host 0.0.0.0 --port 8000

Hosted server

You don't need to run anything to use ByteAsk Embedded Docs. The hosted server gives Claude Code, Codex, Cursor, and any MCP client exact, page-cited facts from embedded and firmware reference docs — register maps, protocol function codes, SCPI commands, standard thresholds, datasheet specs. The guarantee: verbatim source, or "no match" — never an invented value.

This repository is the open-source server that powers that endpoint.

Project layout

src/byteask_embedded_mcp/
  server.py     # FastMCP app + 3 tools (search_docs, get_context, request_document)
  backend.py    # SearchBackend protocol + in-memory SampleBackend (swap for real retrieval)
  render.py     # structured result -> compact markdown
  http_auth.py  # Streamable HTTP entrypoint + stub bearer-token guard
  config.py     # server config (transport, logging, backend selection)
  schemas.py    # Hit / Section result types
  obs.py        # per-call JSONL logging
tests/          # offline unit tests (renderer, backend, server tools)
assets/         # README demo GIF + its deterministic generator

Security

• stdout stays clean in stdio mode (it is the JSON-RPC channel); all logs go to stderr / logs/*.jsonl.
• The HTTP bearer check is a stub — unauthenticated if no token is set, a shared secret at best. Harden it before exposing widely.
• DNS-rebinding protection is on by default for the HTTP transport.

Contributing

PRs and issues are welcome.

uv sync            # install (incl. dev tools)
uv run pytest      # run the offline test suite

A few conventions to keep the server clean:

• The backend seam is the extension point. Retrieval internals (parsing, chunking, embeddings, ranking) are intentionally out of scope here — build them behind SearchBackend in your own package, not in this repo.
• Keep the dependency surface small and the stdio path free of the HTTP stack.
• Add a test for new behavior; the suite is fully offline (no network, no keys).

License

MIT © ByteAsk