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fcvm

io.github.carlosbravoa/fcvmv0.7.0Other

Disposable Firecracker microVM sandboxes for agents: run code, snapshot, fork. Needs Linux with KVM.

The current version, v0.7.0, was published to the official MCP registry on 2026-10-12. It is distributed as fcvm-mcp on PyPI, filed under Other by this index, and declares 9 environment variables. Removals and unreachable sources are measured across every server this index tracks, contract drift across the servers that answer in consecutive snapshots; the index's current counts put this record in context.

In-path gate · all MCP tools

Using fcvm in Claude, Cursor, Gemini CLI, Cline, or Zed?

MCP tool contracts can change remotely with no version bump. The mcpindex gate pins each contract and HOLDs the call when it drifts-before your agent acts. Zero credentials. This is not the package install for this server itself (use Install this server for that).

Install the mcpindex gate (one command)

Rewrites your MCP host config so each server launches behind the gate. Inspect first: curl -fsSL https://mcpindex.ai/install.sh | less

uv tool install mcpindex-gate && mcpindex-config-wire
Auditable install path →Watch it hold a drift →
Trust verdict · v1 advisory · method
REVIEWstatus: PARTIALfresh until 2026-11-12 01:03 UTC
screened 2026-10-13tier: scannedgranularity: description-levelsource: registry

Semantic screen found no manipulation pattern in the description. Conformance probe not yet run.

mcpindex.integrity.descriptionpassINFO

evidence“No malicious instructions”via static_description

Limits of this verdict
  • - Semantic screen only - the deterministic conformance probe has not run on this server
  • - Confidence is reported but not yet calibrated (v1)
  • - Screen reads the tool description, not the live behavior
  • - advisory
  • - registry description only no input schema
  • - screen model 8b

Semantic screen: an LLM judge reads the tool description for hidden instructions (status PARTIAL). A pass means the description is not lying, not that the tool is safe: a high-capability tool with an honest description still warrants caution. The deterministic conformance probe has not been run on this server yet, so the screen here is semantic-only. Posture: advisory. Confidences are reported but not yet calibrated (calibrated=false at v1). Full verdict history is not shown on this page.

Own this server? Test a description on the public screen → It is a separate check from the verdict above, so the two can differ.

That verdict was true at screening time (snapshot 2026-10-20).

Contracts can change after screening, with no version bump. The gate pins fcvm’s tool contracts on first sight and holds any silent change before your agent acts - the check that keeps being true on Tuesday.

See your first HOLD in 2 minutes →

Related: how to trust an MCP server · screen before install · silent contract drift

Cite this record

People vet a server before wiring it in. One line on your project site or docs answers that with an independent record: screening verdict, registry provenance, contract drift history. It stays current as new screens and drift events land.

Markdown
[Independent trust record for fcvm](https://mcpindex.ai/server/io-github-carlosbravoa-fcvm) - screening verdict, registry provenance, and contract drift monitoring.
HTML
<a href="https://mcpindex.ai/server/io-github-carlosbravoa-fcvm">Independent trust record for fcvm</a> - screening verdict, registry provenance, and contract drift monitoring.
Embed this badge

A live verdict badge for your README or listing. It reflects the current screen, links back here, and updates when the verdict does.

Markdown
[![mcpindex](https://mcpindex.ai/api/v1/badge/io-github-carlosbravoa-fcvm)](https://mcpindex.ai/server/io-github-carlosbravoa-fcvm)
HTML
<a href="https://mcpindex.ai/server/io-github-carlosbravoa-fcvm"><img src="https://mcpindex.ai/api/v1/badge/io-github-carlosbravoa-fcvm" alt="mcpindex verdict" height="20" /></a>
Environment variables
FCVM_MCP_NETWORK

Pin the network policy for every sandbox: none, or an allowlist such as @pypi,@github

FCVM_MCP_TEMPLATE

Template used when the agent names neither an image nor a template, e.g. python-sandbox

FCVM_MCP_TTL

Stop sandboxes this long after boot unless the agent sets a lifetime, e.g. 4h

FCVM_MCP_IDLE_STOP

Stop sandboxes that saw no exec or file operation for this long, e.g. 30m

FCVM_MCP_SECRETS

Names of environment variables passed into every sandbox as secrets, e.g. GITHUB_TOKEN

FCVM_MCP_FORWARD

Host credentials relayed into every sandbox: ssh-agent, git

FCVM_MCP_CACHE

1: restricted sandboxes fetch pip and npm packages through the host's mirror

FCVM_MCP_JAIL

0: don't run sandboxes under the Firecracker jailer even when it is set up

FCVM_BIN

Path of the fcvm command, when it isn't on PATH, in ~/.local/bin or in /usr/local/bin

MCP quality score · maturity, not trust · methodology
freshness
25
completeness
20
installability
25
documentation
15
stability
5
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