CorpusFetch

Is CorpusFetch MCP server safe?

• None of the hidden-instruction wordings we know were found in its tool descriptions.
• 0 of its 4 tools are labeled read-only; the others may change or send things.
• Overall it scored 77/100 on 2 Nov 2026.

A test can only see what the server shows from outside, not what it does with your data behind the scenes. Connect servers from makers you trust.

What it can do

4 tools, in the server's own words.

Test results

Safe mode: only tools labeled read-only were run. How the test works

• !
  Ready for the newest MCP version

  1 warning

  • !Uses an older MCP version (2025-06-18). It works today, but it isn't on the July 2026 version (2026-07-28) yet.
  note
• !
  Every tool is described

  1 warning

  • !corpusfetch_lookup_exception and corpusfetch_lookup_symptom have nearly the same description (76% of their words are shared; the only difference: "exception", "python", "class" vs "symptom", "runtime"), so an AI may not know which to pick
  note
• !
  Tools are labeled safe or dangerous

  1 warning

  • !4 of 4 tools have no safety label (read-only or dangerous): corpusfetch_fetch_record, corpusfetch_fetch_warrant, corpusfetch_lookup_exception, corpusfetch_lookup_symptom
  note
• !
  Follows MCP best practices (not scored yet)

  2 tips (not scored)

  • !4 tools not labeled read-only don't say whether running them twice is safe (idempotentHint): corpusfetch_fetch_record, corpusfetch_fetch_warrant, corpusfetch_lookup_exception, corpusfetch_lookup_symptom
  • !4 tools don't say whether they reach outside services like the web (openWorldHint): corpusfetch_fetch_record, corpusfetch_fetch_warrant, corpusfetch_lookup_exception, corpusfetch_lookup_symptom
  note
• ✓
  ConnectsConnected in 651 ms
  pass
• ✓
  Lists its toolsFound 4 tools
  pass
• ✓
  No known hidden instructionsNone of the hidden-instruction wordings we know were found in tool descriptions. New wordings can get past this check.
  pass
• ✓
  Fast enough

  All good

  • ✓Connecting took 651 ms
  • ✓Listing tools took 65 ms
  pass
• –
  Tools work with good inputs

  Not tested

  • –corpusfetch_fetch_record: Not run: no safety label (if you own this server, test again in owner mode)
  • –corpusfetch_fetch_warrant: Not run: no safety label (if you own this server, test again in owner mode)
  • –corpusfetch_lookup_exception: Not run: no safety label (if you own this server, test again in owner mode)
  • –corpusfetch_lookup_symptom: Not run: no safety label (if you own this server, test again in owner mode)
  not tested
• –
  Bad inputs give a clean errorNot tested
  not tested
• –
  Tools work togetherNo safe tool returned data to start a chain from, so chains were not tested (not counted either way)
  not tested
• –
  No secrets leakedNo error messages to check
  not tested

Test it yourself

Free and open source. Same checks, same score.

Show this score on GitHub

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Score over time

• 2 Nov 202677

One test so far. New tests will show here.

Reviews

Coming soon: reviews from people who use CorpusFetch, signed in with GitHub, one per person. Reviews never change the score.