fix(agents): reject a boolean-like tools scalar instead of turning it into a tool name

[L4XB]

Closes #895.

Problem

parseFrontmatter keeps every scalar as a string and parseTools split it on commas, so an agent file with tools: false (a natural way to write "no tools" in YAML) produced a definition whose tools was ["false"]. That token reached the child's tool allowlist as a nonexistent tool name, silently.

Change

parseTools now recognises the YAML scalars that spell a boolean or null (true, false, yes, no, on, off, null, none, ~, case-insensitive) when they arrive as the whole value and reports them through the existing AgentDefinitionError path, the same way unknown thinking levels and modes are rejected: tools "false" is not a tool list; use "tools: []" or omit the key for no tools. A real single tool name, a csv (read, bash), an inline list ([], [read]), a block list, and a missing key parse exactly as before. Items inside an explicit list are not second-guessed.

Tests

New case in tests/agents-config.test.ts covering each rejected spelling (including Off) and the four legitimate forms.

node --experimental-strip-types --test tests/agents-config.test.ts
ℹ tests 10  ℹ pass 10  ℹ fail 0

Summary by CodeRabbit

• Bug Fixes

  • Agent configurations now reject boolean- or null-like scalar values in the tools setting with a clear validation error recommending tools: [].
  • Valid single-tool, comma-separated, empty-list, and missing-tool configurations continue to parse as expected.
  • Invalid tool settings now produce a consistent configuration error without affecting valid agent definitions.

• Tests

  • Added coverage for invalid scalar tool values and existing valid parsing scenarios.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: ASSERTIVE

Plan: Advanced

Run ID: 0a91a71a-9e37-4959-bafb-2459f83282a1

📥 Commits

Reviewing files that changed from the base of the PR and between 045c1ee and f0486dc.

📒 Files selected for processing (2)

• lib/agents-config.ts
• tests/agents-config.test.ts

Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.

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📝 Walkthrough

Walkthrough

parseTools rejects boolean-like scalar values. parseAgentDefinition returns an error for those values and reuses the parsed tools result. Tests cover invalid scalars and valid tool formats.

Changes

Agent tool validation

Layer / File(s)	Summary
Reject invalid scalar tools lib/agents-config.ts	parseTools rejects boolean-like and null-like scalar values. parseAgentDefinition returns an AgentDefinitionError for the resulting error.
Reuse parsed tools and validate formats lib/agents-config.ts, tests/agents-config.test.ts	The agent definition reuses the computed tools value. Tests cover invalid scalar values, valid single tools, CSV values, empty lists, and missing keys.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: alan-thegentleman

Merge Risk: ⚪ Minimal · up to f0486

Boolean- and null-like tool values are rejected as intended, with no identified merge-blocking risk.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: rejecting boolean-like scalar values in the tools field instead of treating them as tool names.
Linked Issues check	✅ Passed	Issue #895 requires boolean-like or null-like scalar values under tools to avoid becoming tool names. lib/agents-config.ts checks scalar values against true, false, yes, no, on, off, `…
Out of Scope Changes check	✅ Passed	The changes are limited to scalar tools validation in lib/agents-config.ts and focused tests in tests/agents-config.test.ts. These changes directly support issue #895. No unrelated behavior is i…

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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