Promptrejectormcp
A security layer that screens user input before it hits your AI agent. Exposes check_prompt, scan_skill, and check_url tools via MCP, plus a parallel REST API for web integrations. Combines Gemini semantic analysis with regex pattern matching to catch prompt injections, jailbreaks, XSS, SQLi, and shell injection attempts. Returns structured severity scores and category tags so you can route critical threats differently than low-risk queries. The skill scanner is built specifically for Claude Code SKILL.md files. Ships with a dynamic pattern library, CVE feed integration, and optional canary token deployment. Runs as stdio transport, requires a Gemini API key, and works alongside output filtering and sandboxing rather than replacing them.
- GitHub stars
- 2
- tools
- 11
- auth
- Secret needed
- transport
- STDIO
- env var
- 1
- last updated
- Jan 28, 2026
Tools
11 toolsPublic tool metadata for what this MCP can expose to an agent.
check_promptScreen a prompt
Screen a prompt
No parameter schema in public metadata yet.
scan_skillScan skill content and its capabilities/model references
Scan skill content and its capabilities/model references
No parameter schema in public metadata yet.
scan_mcp_toolCheck tool descriptions and nested schema text for poisoning
Check tool descriptions and nested schema text for poisoning
No parameter schema in public metadata yet.
check_lethal_trifectaEvaluate private-data access, untrusted input and external egress together
Evaluate private-data access, untrusted input and external egress together
No parameter schema in public metadata yet.
taste_testRun an opt-in Taster/Monitor analysis using mocked tools
Run an opt-in Taster/Monitor analysis using mocked tools
No parameter schema in public metadata yet.
list_patternsBrowse detection patterns
Browse detection patterns
No parameter schema in public metadata yet.
update_vuln_feedsRefresh advisory feeds and draft patterns for review
Refresh advisory feeds and draft patterns for review
No parameter schema in public metadata yet.
verify_pattern_integrityCheck pattern hashes/signatures
Check pattern hashes/signatures
No parameter schema in public metadata yet.
query_cveSearch the configured vulnerability sources
Search the configured vulnerability sources
No parameter schema in public metadata yet.
deploy_canaryCreate a memory/RAG canary token
Create a memory/RAG canary token
No parameter schema in public metadata yet.
verify_canaryCheck content for a canary echo
Check content for a canary echo
No parameter schema in public metadata yet.
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YOUR_API_KEY*secretYour API key for the service
Readme
Prompt Rejector
Screen prompts, skill files and MCP tool descriptions before an AI agent acts on them.
Prompt Rejector combines deterministic security checks, focused TypeSafe AI Jev judgments, and a configurable reasoning model. The active configuration uses TypeSafe and Gemini; Claude and OpenAI adapters are available through model configuration. Your application or agent must call the scanner and act on its decision; installing it does not automatically intercept tool calls.
Try without API keys · Install from source · How we use Jev and our test results · Help wanted · Report a vulnerability
A recorded example
One saved test placed this instruction inside a tool parameter description:
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Details
- Repository
- github.com/revsmoke/promptrejectormcp
- Categories
- AI & LLM Tools, Security & Pentesting
- Package
prompt-rejector- Transport
- STDIO
- Auth
- Required
- Registry
- MCP registry, active
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