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MCP Observatory: one read only walk over every https endpoint in the official registry

by ogasurfproject-jpg · remote · no sign-in to list tools · v0.1.1 · published by GitHub user ogasurfproject-jpg

Public record of one read only walk over the official MCP registry: who answered, tools, who pays.

Changes · 4
CompareRegistry entry

6 tools: 4 change things and 2 only read.

Scanned Oct 21, 2026

No check matched anything in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http hs-observatory https://observatory.horizonshield.dev/mcp

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

6 tools

Changes things 4Claude Code: ask
  • mcp_observatory_disclosure_guideHow the 152 servers that stated who compensates their operator actually did it - the field names observed in the wild, with counts.No findings

    Why it is in this group

    • Nothing in its name or description says what it does, so it is counted as a write.
    Description, as the server wrote it
    How the 152 servers that stated who compensates their operator actually did it - the field names observed in the wild, with counts. Not a specification we invented.
  • mcp_observatory_measure_nowContact one https address now and report what we see: whether it speaks MCP, whether it carries an agent card, and whether that card names who compensates the operator.No findings

    Why it is in this group

    • Nothing in its name or description says what it does, so it is counted as a write.
    Description, as the server wrote it
    Contact one https address now and report what we see: whether it speaks MCP, whether it carries an agent card, and whether that card names who compensates the operator. Read only; no tool is called. robots.txt is read first and honoured. This does NOT change the published record - the next full walk does that. Rate limited, because it contacts somebody else's server on your behalf.
  • mcp_observatory_methodHow the walk was run, what we got wrong and corrected, and the four rules the report holds itself to.No findings

    Why it is in this group

    • Nothing in its name or description says what it does, so it is counted as a write.
    Description, as the server wrote it
    How the walk was run, what we got wrong and corrected, and the four rules the report holds itself to.
  • mcp_observatory_stateWhat was measured, when, over what population, and what the measurement cannot tell you.No findings

    Why it is in this group

    • Nothing in its name or description says what it does, so it is counted as a write.
    Description, as the server wrote it
    What was measured, when, over what population, and what the measurement cannot tell you. Read this before quoting any number from this server.
Only reads 2Claude Code: allow
  • mcp_observatory_lookupWhat happened when we contacted one address, or an aggregate for one host.No findings

    Why it is in this group

    • The name "mcp_observatory_lookup" says "lookup": a word for reading.
    Description, as the server wrote it
    What happened when we contacted one address, or an aggregate for one host. Returns the record hash and the procedure to recompute it. There is no tool here that lists addresses; you must already hold the one you are asking about.
  • mcp_observatory_summaryThe counts, as published and as corrected.No findings

    Why it is in this group

    • The description's first verb is "count": a word for reading.
    Description, as the server wrote it
    The counts, as published and as corrected. How many addresses answered, how many tools they exposed, how many stated who compensates their operator.

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 0.1.1. Values in angle brackets are yours to fill in.

claude mcp add --transport http hs-observatory https://observatory.horizonshield.dev/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json
{
  "permissions": {
    "allow": [
      "mcp__hs-observatory__mcp_observatory_summary",
      "mcp__hs-observatory__mcp_observatory_lookup"
    ],
    "ask": [
      "mcp__hs-observatory__mcp_observatory_state",
      "mcp__hs-observatory__mcp_observatory_disclosure_guide",
      "mcp__hs-observatory__mcp_observatory_measure_now",
      "mcp__hs-observatory__mcp_observatory_method"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as hs-observatory. Review it before you use it.