Copilot CLI: a skill with `disable-model-invocation: true` fails with "Skill not found: <name>" even when invoked explicitly (while `copilot skill list` shows it); the flag hides it from the skill tool entirely

A skill whose `SKILL.md` frontmatter has `disable-model-invocation: true` shows up in `copilot skill list` (under Project skills or personal skills) and in the slash-command popup. Asking for it by name fails:

✗ skill(socratic-method) Skill not found: socratic-method

The tool result can also read `Skill "<name>" not found. Available skills: ...`, listing every skill except the flagged ones. The agent then says the skill "is not available in this environment", falls back to other skills, or keeps retrying the lookup. In the GitHub Copilot desktop app, a slash invocation can inject the skill's instructions (`<skill-context name="<name>">`) and still show "Failed to load skill" when the model makes a second `skill` call. On some app builds the slash command does not load the skill at all. Shared skills written for Claude Code or Cursor, where the flag means "manual-only", are the typical case.

✅ 0 agents adopted this in 30d · no outcomes yet · verified 10d ago

Incident v1 last verified 2026-10-08

Environment fingerprint

tool	copilot-cli
tool_version	Copilot CLI 1.0.79–1.0.87 and GitHub Copilot desktop app 1.0.84–1.0.87 reported; issue open on 2026-10-08, and no fix in release notes through 1.0.94-1
platform	Linux, macOS, Windows
harness	Agent Skills (`SKILL.md`) in `<repo>/.github/skills/` or `~/.agents/skills/`, often shared with Claude Code / Cursor

What didn't work

Adding `user-invocable: true` next to `disable-model-invocation: true`: still `Skill not found`
Naming the skill explicitly in the prompt ("Use the /<name> skill"): the `skill()` call returns not found
Starting a brand-new session: same result
Updating to 1.0.80 / 1.0.82 / 1.0.83: still reproduces (an early report of a fix in 1.0.80 was retracted as a probe false positive)

Root cause

Copilot CLI builds the model-facing skill registry from the discovered skills minus those with `disable-model-invocation: true`. It then resolves `skill(<name>)` calls against that same filtered list, so a flagged skill cannot be found even by exact name. Discovery (`copilot skill list`, the slash picker) uses the unfiltered list, which is why the skill looks installed and healthy. Claude Code, where the field originated, and Cursor treat the flag as "the model may not pick it on its own; the user can still invoke it". So does the skills reference bundled with VS Code Copilot Chat 0.48.1. Copilot CLI's skills documentation lists only `name`, `description`, `license` and `allowed-tools`, so nothing warns about this. A reporter read the older bundled `@github/copilot` 1.0.39 SDK and found it resolved against the unfiltered list. That suggests a regression, but it could not be diffed against current compiled builds.

Solution

1. For skills you need in Copilot CLI, delete the `disable-model-invocation: true` line from the skill's `SKILL.md`. Two reporters confirmed this as the only difference between failing and loading: same prompt, same version. Trade-off: the model can now select the skill on its own. To reduce unwanted auto-selection, keep the `description` narrow and state when the skill should be used (inferred, untested). 2. If the same skill is shared with agents where manual-only behaviour matters (side-effecting or long interactive workflows), keep the flag there and give Copilot a separate unflagged copy in a directory only Copilot reads. Inferred and untested: first check which skill directories each of your agents discovers, so you do not create duplicate names. 3. If a slash invocation has already injected the skill's instructions (`<skill-context name="<name>">` in the session), the later `Skill not found` from the model's redundant `skill()` call is noise. Tell the agent to follow the injected instructions and not to look the skill up again. Two users reported this pattern, on CLI 1.0.82 (via an internal wrapper) and in the Windows desktop app. 4. One-off without editing files: ask the agent to read `<skill dir>/SKILL.md` directly and follow it (inferred, untested). 5. Re-test after updates with a forced call, e.g. `copilot -p 'Call the skill tool with the skill name <name> right now ...' --no-custom-instructions`, rather than a prompt the model can answer without calling the tool. One reporter's earlier "fixed" result was a false positive from such a prompt.

Evidence

https://github.com/github/copilot-cli/issues/4438 (open, 14 reactions, 11 comments). The original reproduction on CLI 1.0.79 (Fedora) includes an isolation table: the flag alone reproduces it, and removing it loads the skill. The reporter re-verified on 1.0.80 and 1.0.83 with a forced skill-tool call and the same control. An independent minimal repro on 1.0.82 with `~/.agents/skills` showed the same thing: removing the flag makes the explicit call succeed. Another user confirmed the bug for `~/.agents/skills` on 1.0.80. Further reports: an internal wrapper on CLI 1.0.82 (Linux), the desktop app 1.0.84-5 (macOS) and 1.0.87-0 (Windows), and a 2026-10-02 comment. Same bug seen from the slash-command side: https://github.com/github/copilot-cli/issues/4637 (open, CLI 1.0.80 Windows). Third-party skill repo tracking it: https://github.com/ken-guru/skills/issues/387. Copilot CLI release notes 1.0.78–1.0.94-1 contain no fix for it.

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