io.github.mrfentmen/regex-mcp

regex-mcp

Is the io.github.mrfentmen/regex-mcp MCP server down? No. It answered initialize and tools/list in the probe of 2026-10-26.

Test, describe, and validate regular expressions locally. No network and no key.

alive probed 2026-11-14 · unchanged since 2026-10-26

2tools

313tokens in Claude Opus 5.5

0.2 %of Claude's 200k window

0.1×the median server

412 msto initialize

10 msto list tools

Run it: npx -y @mrfentmen/regex-mcp@1.0.0 (stdio, probed in a container with the network off)
Host: npmjs.com
Reports itself as: regex-mcp 1.0.0
Capabilities: tools
Instructions: none
Of a 1M window: <0.1 % of a 1M context window
Count: 313 tokens in Claude Opus 5.5, exact, measured 2026-10-26. With the Claude Code prefix mcp__…__ on each tool name: 335. The o200k_base estimate is 168. Counted again when the tool definitions change. Method.
Repository: https://github.com/mrfentmen/regex-mcp
Registry: active, updated 2026-09-21 · registry entry
Changes: 2 recorded, reachable in 2 of them. A row is added when the result, the tool count or the cost changes.

Most expensive tools

The Claude column scales the o200k estimate of each tool by this server's ratio of exact to estimate, 1.86×.

Tool	≈ Claude tokens	o200k estimate	Share of this server
matches	170	91	54 %
test	143	77	46 %

Other registry entries on npmjs.com, the ones next to this name; all of them.

Servers that mention regex.

We add a row when the result changes. A server with no change keeps its last row.

Probed	Result	Init	Tools	Claude	o200k
2026-10-26 07:05	alive	238 ms	2	313	168
2026-10-19 06:54	alive	412 ms	2		168

The result of the latest probe, the tool count and the token cost. The feed has an entry for every probe that changed them.

Stops answering, comes back, tool set or cost changes. One confirmation mail first, a stop link in every mail.