Docs: custom-tools says `tools/` but the loader globs `{tool,tools}` — name one canonical directory

Description

The custom-tools docs name one directory, but the loader accepts two, and the docs name the one that is arguably the less likely to be typed.

https://opencode.ai/docs/custom-tools documents ~/.config/opencode/tools/ (plural). The loader globs {tool,tools}, so a file in either tool/ or tools/ is picked up. In the 1.18.3 binary:

scanSync("{tool,tools}/*.{js,ts}", { cwd: <dir>, absolute: true, dot: true, symlink: true })

Both spellings work today, so this is not a broken feature — it is that the documented contract is narrower than the implemented one. That costs two ways:

• someone who guesses tool/ (singular) gets working behaviour that no page promises, so they cannot tell whether they are relying on something supported;
• anyone documenting, linting or scaffolding against the docs will treat tool/ as wrong, when the loader is happy with it.

Either resolution is fine and both are cheap — document that both are accepted, or narrow the glob to the documented spelling. What would help most is simply naming one as canonical.

Plugins

Not relevant to this report — reproduced with no plugins configured.

OpenCode version

1.18.3

Steps to reproduce

1. Read https://opencode.ai/docs/custom-tools — it specifies ~/.config/opencode/tools/.
2. Place a tool file at ~/.config/opencode/tool/my-tool.ts (singular).
3. Run opencode debug agent build — the tool is registered, despite the directory not matching the documented path.

Screenshot and/or share link

None. The relevant evidence is the glob string in the shipped 1.18.3 binary, quoted above.

Operating System

macOS 26

Terminal

iTerm2