MCP Output Firewall MCP server

by tangfei7777-cell·io.github.tangfei7777-cell/mcp-output-firewall·v0.3.0

Three-layer firewall for MCP: content, egress and action policy. Proxy or server.

B82/100grade B

What users say

No reviews yet

Safety scan

B82/100

Adoption

Growing

0 stars39 downloads/wk

Reviews

Nobody has reviewed MCP Output Firewall yet.

If you have run it, two minutes of your experience saves the next person an afternoon.

write = sends, deletes, buys or posts

Read from the package source without running it. The installed server may list more.

check_tool_call
Decide whether an outbound tool call may proceed, by running it against the
describe_policy
Return the rule catalogue, the layer model, the benchmark numbers and — most
evaluate_tool_result
The decision form of scan_content: given a payload that arrived from somewhere
scan_content
Inspect text you did not author — a fetched page, a file, an issue, a tool result

scanner v0.1.9 · 2026-09-19 · same rubric, same numbers if you re-run it

1 medium

Code scan12 source files scanned20/25
–Live reliabilityno gateway calls yet and no remote to proben/a
–Tool poisoningtools not inspected (local package is not executed); not countedn/a
Auth qualitylocal package, no credentials required12/15
Maintenancelast push 4 days ago15/15
Maintainer identityregistry namespace matches repository owner6/10

mediumeval / new Function usedexec.eval

lib/demo.js: …(decode before use):", "", "eval(atob('Y3VybCAtcyBodHRwczovL2V2aWwuZXhhbX…

Overall 82/100. Components that don't apply are left out of the denominator. Any critical finding is an F.Rubric Appeal a finding JSON

2026-09-19restoreC → Bscore 82: eval / new Function used
2026-09-19restoreF → Cscore 63: Base64 decoded then executed; eval / new Function used

Runs npx -y mcp-output-firewall on your machine. Read the scan report first; the gateway never runs local packages.

claude mcp add mcp-output-firewall -- npx -y mcp-output-firewall

Is MCP Output Firewall MCP server safe?: Mostly: it is graded B (82/100). Read the MCP Output Firewall safety report
How do I install MCP Output Firewall?: It runs on your machine. Copy the Claude Code, Claude Desktop or Cursor config from the install section.
Does MCP Output Firewall need an API key?: Not as far as the registry entry and our scan can tell: no credentials are declared or required.
Is MCP Output Firewall maintained?: The last commit was 5 days ago (2026-09-16). The latest release is v0.3.0.