Guard

Skill PJuniszewski/context-guard/skills/guard

Analyze and prepare prompts with JSON for safe context submissionFrom its SKILL.md

Install

npx -y skills add PJuniszewski/context-guard --skill guard

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

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SKILL.md

2.1 KB, 504 tokens by cl100k_base, as published. Nobody here has run it

Context Guard Skill

Epistemic safety analysis for JSON data in prompts. Prevents LLMs from reasoning with unjustified certainty when input data is incomplete.

Features

Lossless reduction - Minify, columnar transform, remove nulls
Token counting - API or heuristic fallback
Decision engine - ALLOW / SAMPLE / BLOCK
Intelligent trimming - First + last + evenly-spaced sampling
Forensic detection - Warns when specific record queries detected

Usage

When /guard is invoked, execute the guard script:

For file paths:

python3 "${CLAUDE_PLUGIN_ROOT}/scripts/guard_cmd.py" "<file_path>" [options]

For inline JSON data:

python3 "${CLAUDE_PLUGIN_ROOT}/scripts/guard_cmd.py" - [options] <<'GUARD_INPUT'
<json_data>
GUARD_INPUT

Options

Option	Description
`--mode`	analysis\|summary\|forensics (default: auto-detect)
`--force`	Bypass blocks, emit warnings only
`--allow-sampling`	Permit sampling for forensic queries
`--no-reduce`	Skip lossless reduction phase
`--budget-tokens N`	Token budget (default: 3500)
`--print-only`	Output report only, never auto-send
`--json`	Output result as JSON

Semantic Modes

Mode	Sampling	Use Case
`analysis`	Allowed	"What categories exist?", "Price range?"
`summary`	Aggressive	"Describe the data structure"
`forensics`	BLOCKED	"Why did request id=X fail?"

Output

============================================================
CONTEXT GUARD ANALYSIS
============================================================

Decision: [OK] ALLOW | [~] SAMPLE | [X] BLOCK
Mode: analysis | summary | forensics

TOKEN ANALYSIS:
  Original:     5,234 tokens
  After reduce: 4,891 tokens (-343)
  Budget:       3,500 tokens
============================================================

Requirements

Python 3.8+
ANTHROPIC_API_KEY environment variable (for token counting)

What ships with it

Read from the repository

Just SKILL.md. No reference files, no scripts.

Gives 0 of the 12 instructions most quality gates skills give in 504 tokens

Counted across 1,195 of the 2,094 authors here whose files we hold, read 2026-08-07

Read the output and check the exit codein 54 of 1195, across 14 files
Verify requirements using a line-by-line checklistin 53 of 1195, across 12 files
Identify the verification command proving the claimin 51 of 1195, across 12 files
Run the full verification commandin 50 of 1195, across 11 files
Verify output confirms the claimin 49 of 1195, across 12 files
Check version control diff after agent delegationin 46 of 1195, across 6 files
State claim with evidencein 44 of 1195, across 4 files
Run the test suitein 33 of 1195, across 26 files
Keep state in memory by defaultin 27 of 1195, across 6 files
Make prototype runnable with one commandin 26 of 1195, across 5 files
Produce a verification reportin 25 of 1195, across 14 files
Detect the package manager from lockfilesin 24 of 1195, across 5 files

Said here and by no other author read

minify and losslessly reduce input data
count input tokens via api or heuristic
allow sampling for analysis mode
aggressively sample for summary mode
block sampling for forensics mode
emit warnings for forensic record queries

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.