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CaliberAPI MCP server

Which MCP servers are CaliberAPI's own, from the official registry and from asking its own domain, whether they answer, and what they offer. A program checked each of these, nobody copied them from a product page.

read 2026-10-27

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Whose server it is
  • Registry namecom.caliberapi/pistol-opticsverified in the MCP registry

The registry name sits under caliberapi.com. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

When we asked itchecked 2026-10-27
  • Stateanswerschecked 2026-10-27
  • Tools5
  • Server calls itselfcaliberapi
  • Server version1.0.0
  • Protocol version2025-06-18

On 2026-10-27 the server answered initialize and tools/list without a sign-in. First answer in 68 ms.

Should an agent connect itNot proven either way yet
  • Its tools do every use case we checked: check which red dot optics fit a specific pistol; confirm optic fitment against a cited compatibility source.
  • Checked on 1 of the 7 days it takes to judge reliability.

Once connected

  • For "check which red dot optics fit a specific pistol", the likely first call is list_optics_for_pistol.
  • For "confirm optic fitment against a cited compatibility source", the likely first call is check_fit.

Said by rules from the measurements above. The likely first call is a model's pick from the tool list; read its description before relying on it.

Measured dailydaily checks: 1, the first on 2026-10-27
  • INITE MCP scoreafter a weeka score needs 7 daily checks: 1 so far
  • What an agent can do with it2 of 2 use cases
  • Answeredmeasuring1 of the 7 daily checks it takes to print a share
  • Median first answer180 ms
  • Space in an agent's context≈ 955 tokensthe definitions of all its tools (5), which an agent carries on every turn
  • Tool definitionsA · 100 of 100
  • Typed results0 of 5 toolsdeclared outputSchema: results come typed, read once
  • Every tool passes all six checks.

What an agent can do with it

  • can do · check which red dot optics fit a specific pistol
  • not sure · compare direct-mount and adapter plate paths for an optic
  • can do · confirm optic fitment against a cited compatibility source

Each of the product's use cases, put to Jev against this server's tool list: can an agent do it with these tools?

Worth a look

None of the five warning signs in these definitions.

A program checks the server once a day: initialize and tools/list, no model. Tokens are the definitions' length at about four characters a token. The grade averages six checks of every tool's name, description, schema and annotations; it says how well the tools are described, not whether they work. The score weighs what was measured and nothing else: answering (25%), doing the product's job (25%), definitions (20%), context (10%), use (10%) and how readily a client connects (10%). A part that was not measured is left out, and a hidden instruction caps the score at 40. The state of vendors' MCP servers: method and numbers →

Tools it offers5 tools · read 2026-10-27
  • check_fit

    Answer whether a specific red dot optic fits a specific pistol, from source-cited data. Returns fit "direct" (mounts on the slide cut, with the footprint), "adapter" (only through the adapter plate chain in via, with plate maker, model…

  • list_optics_for_pistol

    List every optic with a cited fit on one pistol, each marked direct (with footprint) or adapter (with the plate chain in via). Use it for questions like "what red dots fit my pistol". Optics not listed have no cited fit, which is not…

  • list_pistols_for_optic

    List every pistol with a cited fit for one optic, each marked direct (with footprint) or adapter (with the plate chain in via). Use it for questions like "what pistols take this red dot". Report the answer exactly as returned: never call…

  • get_footprint

    Describe one optic mounting footprint or plate system (for example RMR, RMSc, ACRO, DPP, Glock MOS): screw and recoil lug counts, the optics that use it, the pistols cut for it directly, and the adapter plates that mount or present it…

  • search

    Find pistols, optics and footprints by name. Returns slugs, names and page URLs to pass to the other tools. Use it when you are unsure of an exact model name.

How to connect

Add the server to your MCP client config. Claude Desktop, Cursor and most other clients read this shape:

{
  "mcpServers": {
    "pistol-optics": {
      "type": "http",
      "url": "https://mcp.caliberapi.com/mcp"
    }
  }
}

Add it

Claude Code, in a terminal

claude mcp add --transport http caliberapi https://mcp.caliberapi.com/mcp

Add to CursorAdd to VS Code

claude.ai, ChatGPT and other clients: add https://mcp.caliberapi.com/mcp as a custom connector in the settings.

Each line is something a program found when it went looking: the registry entry, the server's own answer, a spec that parses. A missing line means we did not find it, not that it does not exist.