.NET: [BREAKING] Add auto-approval rules (heuristics) to ToolApprovalAgent

[westey-m]

Summary

Adds configurable auto-approval rules to ToolApprovalAgent, allowing users to supply heuristic functions that can automatically approve function calls without user interaction.

Closes #6083

Changes

New: ToolApprovalAgentOptions class

• JsonSerializerOptions? — moved from the constructor parameter
• IEnumerable<Func<FunctionCallContent, ValueTask<bool>>>? AutoApprovalRules — heuristic functions for auto-approving tool calls

Updated: ToolApprovalAgent

• Constructor now accepts ToolApprovalAgentOptions? instead of JsonSerializerOptions?
• Auto-approval rules are evaluated after standing rules (from prior user approvals) but before prompting the user
• Rules are evaluated in order; first true result auto-approves the call
• Async support via ValueTask<bool> return type

Updated: UseToolApproval extension

• Now accepts ToolApprovalAgentOptions? instead of JsonSerializerOptions?

Updated: HarnessAgent

• Added ToolApprovalAgentOptions? property to HarnessAgentOptions
• Passed through to UseToolApproval() for easy configuration

Evaluation Order

For each ToolApprovalRequestContent:

1. Standing rules (existing "don't ask again" behavior) → auto-approve
2. AutoApprovalRules heuristics in order → first true auto-approves
3. Nothing matches → return to user for manual approval

Tests

• 5 new tests for auto-approval rules (rule approves, rule doesn't match, multiple rules first-match-wins, standing rules take precedence, streaming path)
• 1 new HarnessAgent test for options pass-through
• All existing tests updated for new API signature

[Copilot]

Pull request overview

Adds configurable auto-approval heuristics to the .NET ToolApprovalAgent pipeline, enabling tool calls to be auto-approved (after standing “don’t ask again” rules, before prompting the user), and threads these options through UseToolApproval() and HarnessAgent.

Changes:

• Introduces ToolApprovalAgentOptions to configure both JsonSerializerOptions and ordered AutoApprovalRules.
• Updates ToolApprovalAgent to evaluate heuristic rules in both non-streaming and streaming flows.
• Plumbs ToolApprovalAgentOptions through UseToolApproval() and HarnessAgentOptions.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
dotnet/src/Microsoft.Agents.AI/Harness/ToolApproval/ToolApprovalAgentOptions.cs	Adds new options type including AutoApprovalRules.
dotnet/src/Microsoft.Agents.AI/Harness/ToolApproval/ToolApprovalAgent.cs	Implements heuristic evaluation (standing rules → heuristics → prompt) in both run paths.
dotnet/src/Microsoft.Agents.AI/Harness/ToolApproval/ToolApprovalAgentBuilderExtensions.cs	Switches UseToolApproval to accept ToolApprovalAgentOptions.
dotnet/src/Microsoft.Agents.AI.Harness/HarnessAgentOptions.cs	Adds ToolApprovalAgentOptions pass-through property.
dotnet/src/Microsoft.Agents.AI.Harness/HarnessAgent.cs	Passes ToolApprovalAgentOptions into UseToolApproval().
dotnet/tests/Microsoft.Agents.AI.UnitTests/Harness/ToolApproval/ToolApprovalAgentTests.cs	Updates constructor test + adds heuristic coverage for run and streaming paths.
dotnet/tests/Microsoft.Agents.AI.UnitTests/Harness/ToolApproval/ToolApprovalAgentBuilderExtensionsTests.cs	Updates extension tests for new options parameter.
dotnet/tests/Microsoft.Agents.AI.Harness.UnitTests/HarnessAgentTests.cs	Adds a new test intended to validate options pass-through.

[github-actions]

Automated Code Review

Reviewers: 4 | Confidence: 82% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Design Approach

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