A workflow for changing b4's MCP server, including its tools, descriptions, input schemas, topic text, and write protections. MCP is a standard way for an AI client to call tools provided by another program.

Use it to add or modify MCP tools, tool descriptions, schemas, topics, and write guards in b4's server.

It keeps server changes within the message-size limits and client restrictions that real AI applications impose. It also accounts for protections that prevent unsafe writes.

How DanielLavrushin/b4 configures Claude Code

About the project

B4 is a Linux network packet-processing service that changes network traffic so deep packet inspection systems cannot identify or block its connections. It is used on routers, servers, and desktops to bypass DPI-based blocking, and a router installation can cover devices across the local network. The catalogue lists 12 skills associated with B4.

DanielLavrushin/b4 · 1,848 stars · on GitHub · docs.b4core.app

Reuse

Borrowing it

Nothing to install: this file belongs to DanielLavrushin/b4. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/DanielLavrushin/b4/main/.claude/skills/b4-mcp/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/DanielLavrushin/b4

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/daniellavrushin/b4/b4-mcp/github.svg)](https://agentmods.dev/skills/daniellavrushin/b4/b4-mcp)

Your own site

<a href="https://agentmods.dev/skills/daniellavrushin/b4/b4-mcp"><img src="https://agentmods.dev/badge/skills/daniellavrushin/b4/b4-mcp/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/daniellavrushin/b4/b4-mcp"><img src="https://agentmods.dev/badge/skills/daniellavrushin/b4/b4-mcp.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 114 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,243 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin unknown No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00114	$0.01243
Opus 5.5	$0.00046	$0.00497
Sonnet 5.5	$0.00023	$0.00249
Haiku 4.5	$0.00011	$0.00124

Measured 6d ago against content hash 7cd6e20939b9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

b4-mcp scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/b4-mcp/SKILL.md · 84 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

6d ago First seen · 84 lines · 114 tokens per session scan A 7cd6e20939b9

Subscribe to this mod's changes

b4-mcp is a skill published in the GitHub repository DanielLavrushin/b4 (1,848 stars, last pushed 4d ago), licensed GPL-3.0. It adds 114 tokens to every session and 1,243 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-31.

Backend and APIs Building agents asuswrt asuswrt-merlin censorship censorship-free dpi geosite

b4-mcp next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
b4-mcpDanielLavrushin/b4	Skill	1.8k	4d ago	GPL-3.0	A	114	Claude Code
mem0-oss-to-platformmem0ai/mem0	Skill	68k	2d ago	Apache-2.0	A	217	Claude Code, Codex
azure-mgmt-botservice-dotnetmicrosoft/skills	Skill	3.2k	yesterday	MIT	A	78	Claude Code
fastapi-router-pymicrosoft/skills	Skill	3.2k	yesterday	MIT	A	46	Claude Code
dev-runtimelangwatch/langwatch	Skill	5.0k	yesterday	Apache-2.0	A	172	Claude Code
api-designericrisco/rsc-harness	Skill	503	2d ago	MIT	A	105	Claude Code, Codex
migrate-segw-to-raparc-mcp/arc-1	Skill	252	yesterday	MIT	A	106	Claude Code

b4: Skill for Claude Code