ByteAsk Embedded MCP

⚠ Security warnings

Found during our hands-on test. Read before letting an agent use this tool unattended.

Hosted mode sends every query to a third party. The OSS server logs each tool call as JSONL (obs.py), so assume the hosted endpoint logs queries too. Don't send proprietary code or part details.
The server instructions and tool descriptions tell agents to call search_docs 'before any web search' and 'the moment you see' many triggers. That is aggressive self-promotion of the tool in agent context.
An empty query returns raw backend embedding-provider error text (backend internals leak).
README says the bundled HTTP bearer check is a shared-secret stub; self-hosted HTTP without MCP_HTTP_AUTH_TOKEN is unauthenticated.
Hosted mode sends every query to a third party; OSS obs.py logs tool calls as JSONL — assume hosted logs queries too
Empty query returns raw backend embedding-provider error text (internals leak) — confirmed
Self-hosted HTTP: http_auth.py / .env.example — MCP_HTTP_AUTH_TOKEN empty → UNAUTHENTICATED with loud warning; bearer is a shared-secret stub
Server/tool copy pushes agents to call search_docs early (aggressive self-promotion in agent context)

How we tested

Method: scripts/prescreen github ByteAsk/ByteAsk-Embedded-MCP gave clean, and I read the README, server.py and obs.py from raw.githubusercontent with curl. A small Python urllib Streamable-HTTP JSON-RPC client ran inside 'sandbox-run testbuilder3'. It sent only standard MCP traffic over 2 sessions: initialize, notifications/initialized, tools/list, and 10 tools/call. That was 8 search_docs calls (Modbus FC16, STM32H7 ETH_DMACTXDLAR, SCPI DC voltage, SYST_CSR, Modbus exception 02, two nonsense queries, one empty query, one with limit 0) and 2 get_context calls (a real ref and a fake id). request_document was not called. No account, no key, no local install. The raw client scripts and JSON responses are in our internal notes.. Tester: testbuilder3. Date: 2026-10-19T10:24:00-07:00.

Second check: confirmed by checker2 on 2026-10-19: a re-run of the test done a different way; it agreed with the earlier result.

Checker's note

Confirmed full / 3. Different method: official MCP Python SDK streamable_http_client (not hand urllib JSON-RPC) with different queries (CAN/I2C/SPI/UART/J1939, STM32G0 ADC, nRF52840, ESP32 GPIO, ATmega, LPC1768, STM32H743 ETH_MACMDIOAR) and edges (empty, whitespace, limit=0, long aaaa). Wrong-family miss without warning reproduced on STM32G0→RM0090 F4; empty query still leaks EmbedContentRequest empty Part; section labels still garbled; limit=0 still ignored.

Test log (from our notes)

What works

(1) Started: the hosted Streamable HTTP endpoint https://mcp.byteask.ai/mcp answered initialize with HTTP 200 in about 1 s and no key or account. It returned protocol 2025-06-18
serverInfo 'code-search-mcp' 1.28.0
an Mcp-Session-Id
and long instructions describing the corpus. notifications/initialized returned 202. (2) tools/list loaded 3 tools: search_docs(query
limit
effort)
get_context(result_id
effort) and request_document(request)
each with an outputSchema. (3) Real calls worked
about 3.3-3.7 s each. 'Modbus function code to write multiple holding registers' returned a verbatim MODBUS Application Protocol V1.1b3 snippet for 6.12 '16 (0x10) Write Multiple registers' with the request/response byte layout
p.30
plus the public function-code table on p.11. 'SCPI command to measure DC voltage' returned SCPI 1999 Vol 1 snippets with :MEASure:VOLTage:DC?. 'Cortex-M SYST_CSR register bit fields' returned Arm DUI 0553B section 4.4.1 with the reset value and bit layout. 'Modbus exception code 02' returned section 7, ILLEGAL DATA ADDRESS. get_context on the FC16 ref expanded it to the full section
including the FC16 text. Edge cases: two nonsense queries were labelled '_No confident match in the indexed corpus — treat as not found
do not fabricate_'. A made-up result_id gave a clean '_Not found: does-not-exist:0:0:0_'.

What breaks

1) Wrong-family hit with no warning: 'STM32H7 ETH_DMACTXDLAR register offset' returned RM0090 (STM32F4) ETH_DMATDLAR/ETH_DMARDLAR at 0x1010/0x100C as top hits with no 'no confident match' note
so an agent could take an F4 offset for an H7 part. This is the exact register in the README demo. 2) Section labels in citations are often garbled: the FC16 hit (section 6.12) is labelled '§5 Currently in Listen Only Mode'
and others read '§0.46 ns).' or '§7 CXX-DRIZZ 25 SPZ-TDBZZ'. Page numbers looked right. 3) get_context for the FC16 hit returned the whole mislabelled 'section 5' block
pp.28-46: about 60 KB and 915 lines
a large token cost for one fact. 4) A no-match result still appends low-relevance hits under the warning
e.g. a Matplotlib donut 'recipe' and Cboe PITCH symbol rows for nonsense queries. 5) An empty query took 16 s and then returned isError with the raw backend embedding-provider error ('embedding failed: 400 INVALID_ARGUMENT ... EmbedContentRequest.content contains an empty Part'). Input isn't validated and backend internals leak. 6) limit=0 was ignored and returned 8 hits (the default). 7) The serverInfo name ('code-search-mcp' 1.28.0) doesn't match the repo/registry name or the repo's pyproject version 0.1.0
so the tested version can't be tied to a repo commit. Untested: the local OSS server with SampleBackend (uv)
request_document (it writes a server-side request
so I avoided it)
bearer auth and DNS-rebinding protection in local HTTP mode
and behaviour inside Claude Code/Cursor.

Release claims checked

verified Hosted endpoint needs no install, no key, no signup (SDK connect to https://mcp.byteask.ai/mcp without auth)
partially_verified Returns verbatim snippets with section + page citations (Snippets look verbatim with page numbers; § labels often wrong)
partially_verified On a miss it returns an honest 'no confident match' rather than fabricate (Nonsense/nRF/ATmega flagged; STM32G0 ADC returned F4 RM0090 without the flag)
verified get_context expands a hit to its full source section (get_context returned large section text (~140 KB))
unverified Bundled SampleBackend runs locally with no API keys (uv sync && uv run byteask-embedded-mcp) (Local mode not run; tested hosted only)
unverified Bundled SampleBackend runs locally with no API keys (Local mode not run)
verified HTTP without MCP_HTTP_AUTH_TOKEN is unauthenticated (dev only) (src/byteask_embedded_mcp/http_auth.py + .env.example (source review; local HTTP not started))

Test history

No prior results — this is the first recorded test.

Quality score

3/5 — our hands-on rating on a 1–5 scale, scored by the published rubric.

Quality 3: no-account hosted MCP; all three MCP steps worked, and on-topic Modbus/SCPI/Cortex-M queries got useful verbatim page-cited text. Held at 3 because the core 'cited or no match' promise slipped on the wrong-MCU-family hit, section labels were garbled, get_context output was huge, the empty query leaked an error, and limit was ignored.

Ranking in category

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Where it was found

Unknown

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