Practical AI, worked out in public.https://tinkerhood.com/https://tinkerhood.com/notes/field-notes-001/https://tinkerhood.com/notes/field-notes-001/Our first weekly issue, one skill test across three hosts, a September Claude Code change worth knowing, and one failure we're still chasing.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/create-an-agent-skill/https://tinkerhood.com/learn/create-an-agent-skill/A step-by-step walkthrough of building a small agent skill from a real task, plus where to put the folder for Claude Code and Codex.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/install-skills-in-codex/https://tinkerhood.com/learn/install-skills-in-codex/How we installed the explain-error skill in Codex CLI on both documented project paths, with npx skills add, and confirmed it actually loaded.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/portable-agent-skills/https://tinkerhood.com/learn/portable-agent-skills/We moved a single SKILL.md folder between Claude Code and Codex and checked what travels cleanly, plus documented incompatibilities we haven't hit yet.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/skill-md-format/https://tinkerhood.com/learn/skill-md-format/What goes in a SKILL.md file, which fields the open spec requires, and the complete explain-error example we built and tested against it.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/skill-references-and-assets/https://tinkerhood.com/learn/skill-references-and-assets/What happens when a skill's reference file goes missing on Codex, and why the format validator did not catch it, based on a break we caused on purpose.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/test-an-agent-skill/https://tinkerhood.com/learn/test-an-agent-skill/A four-step testing ladder for agent skills (format, installs, loads, helps) worked through by hand on one real skill, and what each step does not prove.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/what-is-an-agent-skill/https://tinkerhood.com/learn/what-is-an-agent-skill/A plain explanation of agent skills: the SKILL.md file, progressive disclosure, and where the open format is documented as of September 2026.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/where-agent-skills-live/https://tinkerhood.com/learn/where-agent-skills-live/A comparison of documented Claude Code, Codex, and Cursor skill folder paths, marking which ones we tested by hand and which are documented only.Sun, 27 Sep 2026 00:00:00 GMThttps://tinkerhood.com/learn/write-skill-descriptions/https://tinkerhood.com/learn/write-skill-descriptions/What we measured when we compared a vague skill description against a sharp one on Codex, with the trigger counts and a note on sample size.Sun, 27 Sep 2026 00:00:00 GMT