edmundmiller/context-efficiency

Context Efficiency: Filter at the Source

Every token of noise in context is a token the model spends navigating instead of reasoning. Spend a few tokens on a precise query; save many on the backend.

Decision tree

Does the tool support structured output? (--json, -o json, --format json)
├─ Yes → use it, then pipe to jq or python3 -c
└─ No → use grep/awk to pre-filter, or hit the raw API with query params

jq patterns

# Get one field from an array of objects
tool -o json | jq -r '.[0].field'

# Filter array by condition
tool -o json | jq '[.[] | select(.state == "on")]'

# Case-insensitive name search
tool -o json | jq -r '.[] | select(.attributes.friendly_name | test("couch"; "i")) | .entity_id'

# Count by group
tool -o json | jq 'group_by(.state) | map({state: .[0].state, count: length})'

# Pluck two fields
tool -o json | jq -r '.[] | [.entity_id, .state] | @tsv'

python3 -c patterns

# Count by state
tool -o json | python3 -c "
import json, sys; d = json.load(sys.stdin)
from collections import Counter; print(Counter(x['state'] for x in d))
"

# Find matching entity
tool -o json | python3 -c "
import json, sys; d = json.load(sys.stdin)
print(next(x['entity_id'] for x in d if 'couch' in x['attributes'].get('friendly_name','').lower()))
"

Tool-specific examples

Home Assistant (hass-cli)

hass-cli -o json state list 'light.*' | jq -r '.[] | select(.state=="on") | .entity_id'
hass-cli -o json area list | jq -r '.[] | [.area_id, .name] | @tsv'
hass-cli -o json device list | jq '[.[] | select(.area_id == "kitchen")]'

GitHub CLI

gh pr checks 42 --json name,state | jq -r '.[] | select(.state=="FAILURE") | .name'
gh issue list --json number,title,labels | jq '[.[] | select(.labels[].name == "bug")]'
gh api repos/:owner/:repo/pulls --jq '.[].head.ref'

Nix

nix eval .#nixosConfigurations.nuc.config.environment.systemPackages --json | jq -r '.[].name' | grep hass

Database

-- Always: WHERE + LIMIT over SELECT *
SELECT entity_id, state FROM states WHERE domain = 'light' ORDER BY last_changed DESC LIMIT 20;

Anti-patterns

# ❌ dumps hundreds of entities to find one
hass-cli state list

# ✅ returns exactly what you need
hass-cli -o json state list 'light.*' | jq -r '.[] | select(.attributes.friendly_name | test("desk"; "i")) | .entity_id'

# ❌ loads full PR list into context
gh pr list

# ✅ targeted
gh pr list --json number,title --jq '.[] | select(.title | test("fix"; "i"))'