CLI-first guardrail for prompt token, cost, and context observability.
Project description
Token Guardian
Token Guardian is a CLI-first preflight guardrail for LLM prompts.
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[ shielded prompt preflight ]
Before any real model call, it shows:
- estimated tokens
- estimated cost
- context usage
- context risk
- prompt reduction hints
Then it shows the analysis before the execution flow continues.
Preview
Token Guardian opens with an interactive terminal flow that lets developers choose a host profile, select a model, submit a prompt, and inspect the preflight analysis before any real LLM call.
Release Status
Current release: 0.1.0-beta.1
This project is ready for early adopters who want to test a prompt guardrail in real workflows. It is not yet positioned as a fully hardened enterprise product.
What It Is
Token Guardian helps developers inspect a prompt before it reaches an LLM.
It is designed to answer three questions quickly:
- how many tokens this prompt is likely to use
- how much this prompt may cost
- whether this prompt is too large, noisy, or risky for the selected model context
Who It Is For
- developers using LLMs in daily coding workflows
- teams that want a simple prompt review step before execution
- open-source users who want a local, cross-platform CLI
What It Does Not Do
- it does not intercept every editor chat automatically
- it does not enforce organization-wide policy remotely
- it does not replace provider-side safety systems
- it does not depend on MCP or VS Code integration as a product requirement
Why CLI First
This is the most reliable way to enforce a real preflight gate:
- it works on Windows, macOS, and Linux
- it does not depend on editor-specific chat hooks
- it always shows the analysis before any real LLM call
- it is easy to share with other developers
Install
Windows
powershell -ExecutionPolicy Bypass -File scripts\install.ps1
macOS / Linux
bash scripts/install.sh
Run
Windows
powershell -File scripts\run-cli.ps1
macOS / Linux
bash scripts/run-cli.sh
You can also run the command directly:
token-guardian
What the menu does
When the CLI opens, you get a simple menu:
- revisar prompt
- revisar prompt e enviar para LLM
- ver metricas
- listar modelos suportados
- sair
The intended flow is:
- choose the host profile such as
Claude Code,Codex, orGitHub Copilot - choose a suggested model for that profile
- paste the prompt and press
Enter - inspect the markdown analysis
- if you are in execution mode, Token Guardian continues to the LLM automatically
In the interactive terminal flow, selections use espaco to mark and Enter to confirm.
Prompt UX in the current menu:
- the prompt is entered in a single step
Entersends the prompt- output token estimation is automatic in the interactive flow
Main commands
The interactive menu is the default, but advanced commands are still available:
token-guardian
token-guardian menu
token-guardian models
token-guardian metrics
token-guardian review --provider anthropic --model claude-sonnet-4 --prompt "Revise esta arquitetura."
token-guardian run --provider anthropic --model claude-sonnet-4 --prompt "Revise esta arquitetura."
Real LLM invocation
If you want Token Guardian to call the provider after the analysis step, install the gateway extra:
pip install -e .[gateway]
Then use:
token-guardian run --provider anthropic --model claude-sonnet-4 --prompt "Revise esta arquitetura."
The run flow analyzes first and then calls the LLM directly.
Metrics and observability
Token Guardian stores local usage data in SQLite.
Tracked data includes:
- total requests
- total tokens
- estimated cumulative cost
- most used models
- most used providers
Database file:
token_guardian.db
To inspect metrics:
token-guardian metrics
Supported models
See the live list from the CLI:
token-guardian models
Developer commands
Run the full test suite:
pytest
License
MIT
Project details
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