Pull request overview

Introduces a new declarative workflow sample that demonstrates invoking Foundry Toolbox MCP tools, including a reserved tools/list discovery operation. Also extends DefaultMcpToolHandler to support embedded resource content blocks and the new reserved tool name.

Changes:

• Added tools/list reserved tool name support and embedded resource content block conversion in DefaultMcpToolHandler.
• Added new sample InvokeFoundryToolboxMcp (project, YAML, Program.cs) demonstrating provisioning a Foundry toolbox and invoking MCP tools through a declarative workflow.
• Added unit tests covering the reserved tool name handling and embedded resource conversion paths.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 6 comments.

Automated Code Review

Reviewers: 4 | Confidence: 80% | Result: All clear

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

Automated review by peibekwe's agents

Automated Code Review

Reviewers: 4 | Confidence: 86%

✓ Correctness

The PR adds a Foundry Toolbox MCP sample and extends DefaultMcpToolHandler with tools/list discovery and EmbeddedResourceBlock support. The production code is correct: the tools/list branch validates arguments, reuses the MCP client correctly, and serializes tool metadata properly. The EmbeddedResourceBlock handling follows the same patterns as existing Image/Audio content block conversions. The sample code properly uses ConcurrentBag for thread safety and in-memory configuration. No correctness issues found.

✓ Security Reliability

This PR adds a Foundry Toolbox MCP sample and extends DefaultMcpToolHandler with tools/list support and EmbeddedResourceBlock handling. The library changes are well-structured: the reserved tool name check uses strict ordinal comparison, argument validation throws early, the ConvertEmbeddedResource switch handles fallback gracefully, and SerializeToolsList uses Utf8JsonWriter which properly escapes JSON output. The sample code uses ConcurrentBag for thread-safe HttpClient tracking and properly disposes resources in finally blocks. Previously resolved review comments (Description null handling, ConcurrentBag, consolidated branching) have been addressed. No injection risks, resource leaks, or unhandled failure modes were found in the library code.

✓ Test Coverage

Test coverage for the new features is generally solid. The tools/list reserved-tool-name flow, argument rejection, embedded-resource conversion, and executor pass-through are all tested. Two minor gaps stand out: (1) the SerializeToolsList branch that writes a non-null OutputSchema is completely unexercised—only the null/else path runs; (2) the CreateListToolsResultContent test doesn't assert the outputSchema property in the serialized JSON at all, even for the null case it exercises.

✗ Design Approach

I found one design issue in the new workflow sample: it performs tool discovery via tools/list but then ignores the discovered names and hard-codes a derived toolbox tool name instead. The repo already has a better pattern for Foundry toolbox usage that relies on the names returned by ListToolsAsync(), so this sample is coupling itself to a naming convention that the rest of the codebase does not rely on.

Automated review by peibekwe's agents