Once you let an AI agent run shell commands, call APIs, or query a production database on its own, you've effectively hired a very fast new employee who never sleeps, never asks twice, and can be tricked by a cleverly worded prompt into doing something you never intended. A single hijacked instruction or a poisoned tool description can turn a helpful coding agent into the thing that drops a table or leaks a customer list. A new category of tools has grown up specifically to sit between an AI agent and the systems it's allowed to touch — checking every action against a policy, hiding real credentials from the agent, and keeping an audit trail of what actually happened. Here are seven real tools doing that job, from free open-source proxies to enterprise-scale governance platforms.
The short version: if you're a solo developer or small team running Kastra in front of Claude, Cursor or Codex, its sub-millisecond decisions and generous free tier make it the easiest on-ramp. If you want something free and self-hosted with zero licensing cost, Claw Patrol and OneCLI are both fully open source. If your actual worry is API keys leaking rather than agent behavior itself, API Stronghold's ephemeral tokens are built for exactly that. And if you're an enterprise security team that needs visibility across every AI agent and non-human account in the company, Reco is the one built for that scale.
1. Kastra — the easiest way to gate a coding agent's real-world actions
Kastra is a runtime authorization layer built specifically for agents running on Claude, Cursor, Codex and OpenClaw. It checks every shell command, API request, database query or browser action the agent tries to take against a policy in under a millisecond, and can revoke access instantly if something looks wrong. It ships SDKs across TypeScript, Python, Go, Rust, Java and Swift, plus signed append-only audit trails and both cloud and air-gapped self-hosted deployment.
Pricing: free for up to 50,000 decisions/month; Pro $19.99/dev/month (1M decisions); Team $49.99/dev/month (10M decisions); Enterprise on quote.
Watch out for: it's a genuinely new category with little field track record, per-developer pricing can climb fast on a large team, and there are no publicly named customers yet to check references against.
Pick Kastra if: you're running Claude/Cursor/Codex agents against production systems and want SOC 2/HIPAA/GDPR-grade controls without building the gating logic yourself.
2. Claw Patrol — free, open source, and it inspects SQL and Kubernetes calls directly
Claw Patrol is an MIT-licensed open-source agent proxy built by the Deno team. Instead of filtering at the prompt level, it intercepts traffic at the protocol level — HTTP, SQL (Postgres, ClickHouse), and Kubernetes API calls — so a rule can block any DROP TABLE outright, no matter how the agent phrased the request. Ambiguous actions can be routed to an LLM judge or a human approver over Slack, and the agent itself never sees real credentials.
Pricing: completely free (MIT license). The real cost is engineering time — it's self-hosted only, over WireGuard or Tailscale, with rules written by hand in HCL.
Watch out for: it's alpha-stage software with no managed SaaS option, and every team has to write its own rule set from scratch.
Pick Claw Patrol if: you have the DevOps capacity to self-host, and you want protocol-level control (especially over SQL and Kubernetes) rather than just prompt-level filtering.
3. OneCLI — hides real API keys from the agent entirely
OneCLI is an open-source (Apache 2.0) credential gateway: agents make normal API calls using placeholder tokens, and a small Rust-based gateway swaps in the real, AES-256-GCM-encrypted credential only at the moment a request actually leaves for the real service. It works across MCP servers, CLI tools, curl commands and agent code, with endpoint blocking, per-agent rate limiting and approval workflows for sensitive operations, all managed from a Next.js dashboard.
Pricing: free for up to 2 agents, no credit card. Paid tiers exist for more agents and enterprise features, though pricing beyond the free tier isn't fully public.
Watch out for: it's a young, community-scale project rather than an enterprise-hardened vault, and it overlaps in purpose with general secrets managers like Vault or Infisical.
Pick OneCLI if: your main worry is an agent leaking or misusing a real API key, and you want a one-line, self-hostable fix rather than a full policy engine.
4. API Stronghold — short-lived, traceable tokens instead of long-lived keys
API Stronghold takes a different angle on the same problem: it never hands out a real key at all. Real credentials sit in a zero-knowledge-encrypted vault, and every consumer — a script, a CI job, an agent — gets a scoped "phantom" token that expires on a minute-level timescale. It includes a CLI for managing environment variables, one-click sync to Vercel, GitHub and AWS, and automated key rotation measured in seconds.
Pricing: free tier available with no credit card required; paid tiers exist but aren't detailed publicly.
Watch out for: it's less established than Doppler or HashiCorp Vault, and there's little public information about the team or funding behind it.
Pick API Stronghold if: you want to shrink the blast radius of a leaked key to minutes instead of indefinitely, without adopting a full agent-policy platform.
5. Lineation — a full control plane with a distinct identity per agent
Lineation goes further than a credential gateway: it gives each AI agent its own "non-human identity" under zero-trust rules instead of letting agents share generic API keys, inspects prompts and tool calls in real time for injection attempts, redacts PII and secrets before they leak, and runs agent actions inside a sandbox. It ships an MCP gateway, a multi-provider LLM gateway (OpenAI, Claude, Google, Azure), policy-as-code governance, and immutable audit trails with replay.
Pricing: free up to 5,000 protected actions/month; Growth $249/month (50k actions); Team $1,399/month (1M actions); Enterprise on quote with on-premises deployment.
Watch out for: usage-based pricing can get expensive at real production volume, and there's no public information on how long the company has existed.
Pick Lineation if: you're running agents across multiple LLM providers and want one control plane — identity, injection detection, PII redaction and audit — instead of stitching together several point tools.
6. Gopher MCP — purpose-built for securing the MCP protocol itself
Gopher MCP narrows in on one specific attack surface: the Model Context Protocol connections that let Claude, Cursor and similar assistants call real internal tools. It inspects every MCP tool call in real time, blocks known attack patterns like tool poisoning and prompt injection, enforces zero-trust access control down to the parameter level (an agent can read a table but be blocked from deleting it), and encrypts peer-to-peer connections with post-quantum cryptography.
Pricing: not published — the team offers custom quotes and a 30-day trial.
Watch out for: its scope is narrow by design (MCP specifically, not general AI security), and there's little independent track record on the product yet.
Pick Gopher MCP if: your agents connect to internal tools via MCP specifically, and you want dedicated tool-poisoning and prompt-injection detection rather than a general-purpose gateway.
7. Reco — enterprise-wide visibility into every AI agent and non-human account
Reco operates at a different altitude entirely: instead of gating one agent's actions, it maps every SaaS app, AI agent and automated service account across an entire company, so a security team can see what actually has access to what. It combines AI agent discovery, identity governance for human and non-human accounts, 1,000+ pre-built threat detection controls with auto-remediation, data exposure management, and a no-code integration engine.
Pricing: not public — enterprise sales process, explicitly targeting Fortune 500-scale organizations.
Watch out for: it's built for enterprise scale and is likely overkill for a small team, and it overlaps with broader SaaS security posture tools if AI-agent governance isn't your specific pain point.
Pick Reco if: you're a large organization that has lost track of how many AI agents and service accounts are quietly running with access to real data.
Quick comparison
| Tool | Best for | Pricing model |
|---|---|---|
| Kastra | Gating Claude/Cursor/Codex agent actions | Free up to 50k decisions; from $19.99/dev/mo |
| Claw Patrol | Free, protocol-level (SQL/K8s) control | Free, open source (self-hosted) |
| OneCLI | Hiding real API keys from agents | Free up to 2 agents |
| API Stronghold | Short-lived, traceable tokens | Free tier, paid undisclosed |
| Lineation | Multi-LLM control plane + identity | Free up to 5k actions; from $249/mo |
| Gopher MCP | Securing MCP tool calls specifically | Quote-only, 30-day trial |
| Reco | Enterprise-wide agent/identity visibility | Quote-only, enterprise |
None of these tools make an AI agent trustworthy on its own — that still comes down to how carefully you scope what it's allowed to do. What they remove is the all-or-nothing risk of an agent holding a real API key or admin password with no checkpoint in between. If you're a solo developer or small team, Claw Patrol or OneCLI cost nothing to try. If you want a managed product with compliance certifications behind it, Kastra and Lineation are built for that. And if your problem is really "how many agents do we even have running right now," Reco is the one answering that question at company scale.