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[FEATURE] Add Anthropic Advanced Tool Use beta support - #7390

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[FEATURE] Add Anthropic Advanced Tool Use beta support#7390
theslyprofessor wants to merge 1 commit into
anomalyco:devfrom
theslyprofessor:feat/advanced-tool-use

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@theslyprofessor

@theslyprofessortheslyprofessor commented Jan 8, 2026

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Summary

Adds support for Anthropic's Advanced Tool Use beta features via feature flag.

Closes#4713

Motivation

OpenCode currently loads all MCP tool definitions upfront. For power users with multiple MCP servers, this creates high token costs (50K-100K+ tokens before any work begins).

Anthropic released beta features specifically designed to address this:

  • 85% token reduction with Tool Search Tool
  • 37% token reduction with Programmatic Tool Calling
  • Significant accuracy improvements with Tool Use Examples

This PR adds the foundation for these capabilities.

Changes

Beta Header Support

Added OPENCODE_ADVANCED_TOOL_USE feature flag that enables the advanced-tool-use-2025-11-20 beta:

// packages/opencode/src/provider/provider.tsconstadvancedToolUseEnabled=Env.all()["OPENCODE_ADVANCED_TOOL_USE"]==="true"constbetaFeatures=["claude-code-20250219","interleaved-thinking-2025-05-14","fine-grained-tool-streaming-2025-05-14",]if(advancedToolUseEnabled){betaFeatures.push("advanced-tool-use-2025-11-20")}

Usage

export OPENCODE_ADVANCED_TOOL_USE=true
opencode

Breaking Changes

None. Feature flag defaults to false. Without the flag, OpenCode behaves exactly as before.

Testing

  • ✅ Typecheck passes
  • ✅ No breaking changes introduced
  • ✅ Feature flag defaults to off (safe to merge)

Next Steps

This PR lays the foundation for:

  1. Tool Search Tool - defer_loading config for MCP tools
  2. Programmatic Tool Calling - Code execution sandbox
  3. Tool Use Examples - input_examples in tool schemas

I can implement these in follow-up PRs if this approach is approved.

References

Author Notes

I'm a power user running OpenCode with 9+ MCP servers. This feature would save me 50K-70K tokens per session. Happy to implement the full feature set if this foundation is accepted.

Thanks for reviewing! 🚀

@theslyprofessor
feat: Add Anthropic Advanced Tool Use beta support
fa61a86
Adds support for Anthropic's Advanced Tool Use beta features via
feature flag.
Features enabled by this beta:
- Tool Search Tool: On-demand tool discovery (85% token reduction)
- Programmatic Tool Calling: Code-based tool orchestration
- Tool Use Examples: Example-based learning for better accuracy
Usage:
export OPENCODE_ADVANCED_TOOL_USE=true
opencode
When enabled, adds 'advanced-tool-use-2025-11-20' to the
anthropic-beta header. When disabled, OpenCode behaves exactly
as before.
This is the foundation for implementing:
1. defer_loading config for MCP tools
2. Code execution sandbox for tool orchestration
3. input_examples for tool schemas
Related:
- Issue anomalyco#4713
- Anthropic docs: https://www.anthropic.com/engineering/advanced-tool-use
Tested:
- Typecheck passes
- No breaking changes
- Feature flag defaults to off
CopilotAI review requested due to automatic review settings January 8, 2026 23:01
@github-actions

github-actionsBot commented Jan 8, 2026

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Hey! Your PR title [FEATURE] Add Anthropic Advanced Tool Use beta support doesn't follow conventional commit format.

Please update it to start with one of:

  • feat: or feat(scope): new feature
  • fix: or fix(scope): bug fix
  • docs: or docs(scope): documentation changes
  • chore: or chore(scope): maintenance tasks
  • refactor: or refactor(scope): code refactoring
  • test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

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The following comment was made by an LLM, it may be inaccurate:

No duplicate PRs found

CopilotAI reviewed Jan 8, 2026
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Pull request overview

This PR adds support for Anthropic's Advanced Tool Use beta features through a feature flag OPENCODE_ADVANCED_TOOL_USE. When enabled, it includes the advanced-tool-use-2025-11-20 beta header in Anthropic API requests, providing foundation for future token reduction features.

Key Changes:

  • Adds OPENCODE_ADVANCED_TOOL_USE environment variable support
  • Refactors hardcoded beta headers into a dynamic array
  • Conditionally includes advanced tool use beta based on feature flag

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Comment threadpackages/opencode/src/provider/provider.ts
const CUSTOM_LOADERS: Record<string, CustomLoader> = {
async anthropic() {
// Add advanced tool use beta if feature flag is enabled
const advancedToolUseEnabled = Env.all()["OPENCODE_ADVANCED_TOOL_USE"] === "true"

CopilotAIJan 8, 2026

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The feature flag should be defined in the Flag namespace (flag/flag.ts) using the truthy() helper function, consistent with other feature flags in the codebase. This approach provides a centralized location for all flags, makes them easier to discover, and follows the established pattern used by flags like OPENCODE_ENABLE_EXPERIMENTAL_MODELS, OPENCODE_DISABLE_CLAUDE_CODE, etc.

Suggested change
constadvancedToolUseEnabled=Env.all()["OPENCODE_ADVANCED_TOOL_USE"]==="true"
constadvancedToolUseEnabled=Flag.truthy("OPENCODE_ADVANCED_TOOL_USE")

Copilot uses AI. Check for mistakes.
Comment threadpackages/opencode/src/provider/provider.ts
"fine-grained-tool-streaming-2025-05-14",
]

// Add advanced tool use beta if enabled

CopilotAIJan 8, 2026

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This comment is redundant with the comment on line 76. Consider removing one of them to reduce duplication.

Suggested change
// Add advanced tool use beta if enabled

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@github-actionsgithub-actionsBot mentioned this pull request Jan 12, 2026
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@thdxr
thdxrforce-pushed the dev branch 3 times, most recently from f1ae801 to 08fa7f7CompareJanuary 30, 2026 14:37
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github-actionsBot commented Mar 10, 2026

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Closing this pull request because it has had no updates for more than 60 days. If you plan to continue working on it, feel free to reopen or open a new PR.

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[FEATURE]: Claude Advanced Tool Usage

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