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Constitutional guardrails and loop detection for AI agents
About
Constitutional guardrails and loop detection for AI agents
Security Report
4.8
Use Caution4.8High RiskAgent-guard-mcp is a well-structured MCP server for detecting infinite agent loops with appropriate authentication, input validation, and permissioning. The codebase uses standard MCP SDK patterns and Zod validation. No critical vulnerabilities or malicious patterns detected. Minor code quality findings do not significantly impact security posture. Supply chain analysis found 4 known vulnerabilities in dependencies (0 critical, 3 high severity). Package verification found 1 issue.
4 files analyzed · 9 issues found
Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.
Permissions Required
This plugin requests these system permissions. Most are normal for its category.
How to Install
Add this to your MCP configuration file:
{
"mcpServers": {
"io-github-mdfifty50-boop-agent-guard": {
"args": [
"-y",
"agent-guard-mcp"
],
"command": "npx"
}
}
}Documentation
View on GitHubFrom the project's GitHub README.
agent-guard-mcp
MCP server that detects and prevents infinite agent loops — the #1 reliability problem in agentic systems.
Provides circuit breakers, pattern detection, stuck-agent analysis, and recovery recommendations via the Model Context Protocol.
Install
npx agent-guard-mcp
Claude Desktop
Add to claude_desktop_config.json:
{
"mcpServers": {
"agent-guard": {
"command": "npx",
"args": ["agent-guard-mcp"]
}
}
}
From source
git clone https://github.com/mdfifty50-boop/agent-guard-mcp.git
cd agent-guard-mcp
npm install
node src/index.js
Tools
register_agent
Register an agent for monitoring.
| Param | Type | Default | Description |
|---|---|---|---|
agent_id | string | required | Unique agent identifier |
max_iterations | number | 100 | Max iterations before forced stop |
progress_threshold | number | 0.3 | Min unique/total action ratio to be "making progress" |
log_action
Log an agent action for loop detection. Maintains a rolling window of the last 50 actions.
| Param | Type | Default | Description |
|---|---|---|---|
agent_id | string | required | Agent identifier |
tool_name | string | required | Tool being called |
args | object | required | Arguments passed |
result_preview | string | "" | Brief result preview (max 200 chars) |
Returns early warnings when repeated patterns are detected.
detect_loop
Check if an agent is stuck in an infinite loop.
| Param | Type | Description |
|---|---|---|
agent_id | string | Agent to check |
Returns:
is_stuck— booleanconfidence— 0.0 to 1.0pattern—healthy,exact_repeat,low_diversity, orexact_repeat_and_low_diversitysuggestion— human-readable recovery advicerepeated_actions— list of repeated signatures with counts
set_circuit_breaker
Configure automatic intervention when action patterns repeat.
| Param | Type | Default | Description |
|---|---|---|---|
agent_id | string | required | Agent identifier |
max_repeats | number | 3 | Trigger after N identical actions |
action | string | "warn" | "warn", "block", or "suggest_alternative" |
check_circuit_breaker
Pre-flight check before executing a tool. Call this BEFORE the actual tool call.
| Param | Type | Description |
|---|---|---|
agent_id | string | Agent identifier |
proposed_tool | string | Tool about to be called |
proposed_args | object | Arguments about to be passed |
Returns proceed: false when the circuit breaker fires (block mode only).
get_stuck_report
Detailed analysis of why an agent is stuck.
| Param | Type | Description |
|---|---|---|
agent_id | string | Agent to analyze |
Returns: action history, pattern analysis, token waste estimate, diversity ratio, top repeated patterns, and recovery recommendations.
get_health_dashboard
Overview of all monitored agents. No parameters.
Returns all agents sorted by risk score with their status (STUCK/HEALTHY), action counts, and circuit breaker config.
Resources
| URI | Description |
|---|---|
agent-guard://agents | All monitored agents with current status |
Usage Pattern
1. register_agent — at agent startup
2. Before each tool call:
a. check_circuit_breaker — should this action proceed?
b. Execute the tool
c. log_action — record what happened
3. Periodically:
- detect_loop — am I stuck?
- get_health_dashboard — how are all agents doing?
4. On stuck detection:
- get_stuck_report — what went wrong and how to recover
Tests
npm test
License
MIT
Reviews
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