A local runtime for AI agents, installed from an npm package and connected through MCP, a standard way for agents to use external tools.

Running the String runtime on your computer and adding it to an agent setup with npx.

It gives agents a locally running environment instead of requiring a separate hosted service. The description does not provide enough detail to explain its other benefits.

string — MCP server by string-os

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add mcp/string-os/string/string

Clone the repo

git clone --depth 1 https://github.com/string-os/string

Made for: Claude Code, Codex, Cursor, Gemini CLI, OpenCode.

Per session not measured What this adds to a session before it is invoked.

When invoked not measured Not applicable: nothing here is loaded into a session.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

string 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 yesterday.

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.

.mcp.json · 10 lines

What it actually says

{
  "string": {
    "command": "npx",
    "args": [
      "-y",
      "@string-os/[email protected]",
      "--mcp"
    ]
  }
}

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.

yesterday First seen · 10 lines scan A 37471bdf4f3b

Subscribe to this mod's changes

string is an MCP server published in the GitHub repository string-os/string (65 stars, last pushed 13d ago), licensed MIT. Its token cost is not measured: an MCP server costs its tool schemas, not its config file. 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 2026-08-30.

Data and AI LLM agent-runtime agent-skills ai-agents cli commonmark

string

Getting it into your agent

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

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