Allow selecting which MCP tools to expose

[Microck]

Closes #201.

Add mutually exclusive --tools and --exclude-tools comma-separated filters, with KAGI_MCP_TOOLS as an environment allowlist. Either CLI flag overrides the environment. Trim whitespace, deduplicate names, reject unknown or empty names at startup, and retain deterministic catalog ordering.

Filter the shared tool catalog so stable and draft discovery and calls agree; hidden tools return an unknown-tool JSON-RPC error. An allowlist containing a mutating tool requires --enable-mutating-tools. With no filter, preserve existing behavior.

Add seven integration tests covering both wire protocols, exclusions, CLI/environment precedence, startup errors, mutation permission, hidden calls and server liveness, and empty catalogs. Document usage and update the changelog.

Validation for 4c6269b:

• CI passed: formatting, clippy with warnings denied, cargo check, and 329 tests passed (13 existing tests ignored).
• All seven new filter regression tests passed.
• Coverage and Security workflows passed.
• Both actual x86_64 and aarch64 musl release builds passed static ELF checks and --version/--help smoke tests.
• Documentation preview deployed successfully; git diff --check passed.

Summary by CodeRabbit

• New Features
  • Choose which tools are available through kagi mcp by allowing specific tools or excluding selected tools. Configure an allowlist with KAGI_MCP_TOOLS or command-line options.
  • Tool filters apply to both stable and draft protocols. Names are case-sensitive; unknown or empty names cause startup errors, and command-line filters take precedence over the environment setting.
  • Calls to hidden tools return an unknown-tool error. Mutating tools still require explicit opt-in, and excluding all tools results in an empty catalog.

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Project	Deployment	Actions	Updated
docs	Ready	Preview	Oct 9, 2026 11:40am UTC

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Repository: Microck/kagi-cli/.coderabbit.yaml
• Review profile: CHILL
• Plan: Advanced
• Run ID: 34be0e22-25ac-4826-81f8-aa32362c5685

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📥 Commits

Reviewing files that changed from the base of the PR and between c9843f6 and 4c6269b.

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📒 Files selected for processing (5)

• CHANGELOG.md
• docs/content/docs/commands/mcp.mdx
• src/cli.rs
• src/main.rs
• tests/integration-cli.rs

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📝 Walkthrough

Walkthrough

The MCP command now supports tool allowlists and exclusions through CLI options or KAGI_MCP_TOOLS. It validates filter names, applies filters to the exposed catalog, and returns an unknown-tool error for calls to filtered tools.

Changes

MCP tool filtering

Layer / File(s)	Summary
Filter options and documented behavior src/cli.rs, docs/content/docs/commands/mcp.mdx, CHANGELOG.md	The CLI adds --tools and --exclude-tools. The documentation and changelog describe filter inputs, precedence, validation, and mutating-tool requirements.
Filter application src/main.rs	McpServerConfig::with_tool_filter validates and applies selected names. run_mcp reads KAGI_MCP_TOOLS when neither CLI filter is set.
Filter integration tests tests/integration-cli.rs	Tests cover CLI and environment filters, validation errors, mutating-tool opt-in, filtered calls, empty catalogs, and test environment cleanup.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant Client as MCP client
  participant CLI as kagi mcp CLI
  participant Runner as run_mcp
  participant Config as McpServerConfig
  Client->>CLI: Start with filter arguments
  CLI->>Runner: Pass MCP arguments
  Runner->>Config: Apply inclusion and exclusion filters
  Client->>CLI: Request tools/list
  CLI-->>Client: Return filtered tool catalog
  Client->>CLI: Call a hidden tool
  CLI-->>Client: Return unknown-tool JSON-RPC error

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Suggested reviewers: joilence

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Merge Risk: ⚪ Minimal · up to 4c626

The tool filters appear ready to merge after normal checks; empty filter values are rejected at startup.

🚥 Pre-merge checks | ✅ 5 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 57.14% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 14 functions across 3 files. (2 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check		The PR implements the coding requirements in directly linked issue #201. It adds --tools and --exclude-tools, supports the KAGI_MCP_TOOLS allowlist, rejects unknown and empty names, and applies …
Out of Scope Changes check		The changes remain within issue #201. CLI and server filtering implement tool selection. Integration tests verify the filtering behavior. Documentation and changelog updates describe the new interface…
Release Metadata Consistency		All required release metadata matches. Cargo.toml, Cargo.lock's kagi package entry, and npm/package.json each declare version 0.21.1. CHANGELOG.md contains the matching ## [0.21.1] heading.
Title check		The title is concise and clearly describes the main change: selecting which MCP tools to expose.
Description check		The description clearly explains what changed and why, documents verification results, and notes the changelog and documentation updates. It does not include the template's Auth / Secrets section, but…

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Full details: Docstring Coverage

Explanation

Docstring coverage is 57.14% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 14 functions across 3 files. (2 skipped: 2 unsupported.)

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Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-09T11:42:28.483814Z	4c6269b	Draft marked ready

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