feat: add Foundry agent validation skill entry point

[Xiaofu Huang (XiaofuHuang)]

Description

• add a standalone, read-only Foundry hosted-agent validation sub-skill
• support default or custom validation rules with structured JSON and Markdown reports
• add a sample recommendation to configure MCP servers in Foundry Toolbox and access them through the Toolbox consumer endpoint
• keep the validation sub-skill disconnected from the parent microsoft-foundry routing for now

Future integration

When the validation flow and its integration coverage are ready, add this sub-skill to microsoft-foundry/SKILL.md with narrow routing for explicit hosted-agent best-practice validation requests.

Checklist

• Tests pass locally (cd tests && npm test)
• Title has one of the prefixes: fix:, feat:, feature:, chore:, misc:, test:, eval:
• If modifying skill descriptions: verified routing correctness with integration tests (In tests/, npm run test:vally -- --plugin <plugin-dirname> --skill <skill>)

[Copilot]

Pull request overview

This PR adds a new Foundry hosted-agent validation sub-skill entry point under the existing microsoft-foundry/foundry-agent content, defining a read-only workflow that evaluates a hosted agent against best-practice rules and emits structured JSON + Markdown reports.

Changes:

• Added a validation workflow document (validate.md) that defines path resolution, rule selection/validation, rule execution semantics, and report generation.
• Introduced JSON Schemas for custom rule files and validation reports, plus a Markdown report template.
• Added an initial default rules YAML containing a Toolbox/MCP best-practice recommendation.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
plugins/azure-skills/skills/microsoft-foundry/foundry-agent/validate/validate.md	Defines the end-to-end hosted-agent validation workflow and behavioral constraints.
plugins/azure-skills/skills/microsoft-foundry/foundry-agent/validate/references/rules-schema.json	Adds a JSON Schema for validating custom rule files.
plugins/azure-skills/skills/microsoft-foundry/foundry-agent/validate/references/report-schema.json	Adds a JSON Schema for the generated validation report format.
plugins/azure-skills/skills/microsoft-foundry/foundry-agent/validate/references/report-template.md	Adds the Markdown template for human-readable validation results.
plugins/azure-skills/skills/microsoft-foundry/foundry-agent/validate/references/default-rules.yaml	Seeds a default rule set focused on Toolbox-based MCP consumption.

Suppressed comments (1)

plugins/azure-skills/skills/microsoft-foundry/foundry-agent/validate/references/rules-schema.json:85

• rules-schema.json doesn’t set additionalProperties: false for the root schema or for each rule object, so typos/unknown fields in custom rules can silently pass validation. Tightening this makes the “list all errors and stop” behavior more reliable.

            }
          }
        }
      }
    }
  }
}

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