Lettance

Is Lettance MCP server safe?

• No hidden instructions were found in its tool descriptions.
• Its error messages showed no secrets or internal details.
• All 7 of its tools are labeled read-only.
• Overall it scored 95/100 on 31 Oct 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

7 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 (2025-11-25). It works today, but it isn't on the July 2026 version (2026-07-28) yet.
  note
• ✓
  ConnectsConnected in 633 ms
  pass
• ✓
  Lists its toolsFound 7 tools
  pass
• ✓
  Every tool is describedAll 7 tools and their inputs are described
  pass
• ✓
  Tools are labeled safe or dangerousEvery tool has a safety label
  pass
• ✓
  No hidden instructionsNo hidden instructions found in tool descriptions
  pass
• ✓
  Tools work with good inputs

  All good

  • ✓check_address: Answered with an error, probably because of our sample input: {"error":"No such postcode: test"} {"error":"No such postcode: test"}
  • ✓search_rules: Worked (237 ms)
  • ✓get_rule: Answered with an error, probably because of our sample input: {"error":"No rule with that id; use search_rules."} {"error":"No rule with that id; use search_rules."}
  • ✓council_licensing: Answered with an error, probably because of our sample input: {"error":"No English council matches 'test'. Pass a council slug such as 'southwark' or its name.","councils":"https://lettance.com/council…
  • ✓plan_rental: Answered with an error, probably because of our sample input: {"error":"Enter a full UK postcode, for example SW9 7AA."} {"error":"Enter a full UK postcode, for example SW9 7AA."}
  • ✓compare_addresses: Answered with an error, probably because of our sample input: Invalid tool arguments; check the tool input schema.
  • ✓area_market: Answered with an error, probably because of our sample input: {"error":"No such postcode: test"} {"error":"No such postcode: test"}
  pass
• ✓
  Bad inputs give a clean error

  All good

  • ✓check_address: Refused missing required input "postcode" with a clear error
  • ✓check_address: Refused wrong type for "postcode" with a clear error
  • ✓search_rules: Refused missing required input "query" with a clear error
  • ✓search_rules: Refused wrong type for "query" with a clear error
  • ✓get_rule: Refused missing required input "id" with a clear error
  • ✓get_rule: Refused wrong type for "id" with a clear error
  • ✓council_licensing: Refused missing required input "council" with a clear error
  • ✓council_licensing: Refused wrong type for "council" with a clear error
  • and 6 more
  pass
• ✓
  Tools work togethersearch_rules → get_rule: get_rule found what search_rules returned (id = "electrical-inspection-every-5-years")
  pass
• ✓
  Fast enough

  All good

  • ✓Connecting took 633 ms
  • ✓Listing tools took 193 ms
  • ✓Average tool answer: 199 ms
  • ✓search_rules: Slowest tool: search_rules (237 ms)
  pass
• ✓
  No secrets leakedChecked 21 error messages: no secrets or internal details
  pass
• ✓
  Follows MCP best practices (not scored yet)Tool names, safety labels and tool list size follow the MCP guide
  pass

Test it yourself

Free and open source. Same checks, same score.

Show this score on GitHub

Free for every server in the directory. Paste this into your README: the badge shows the score from our latest test.

Score over time

• 31 Oct 202695

One test so far. New tests will show here.

Reviews

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