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SergeyMenshykh be8d2619e4 Python: [Breaking] Restructure agent skills to use multi-source architecture (#5584)
* migrate skills to multi source architecture

* Fix ruff lint errors in skills module (ASYNC240, SIM108, E501)

- Use anyio.Path for async file I/O in _FileSkillResource.read()
- Use noqa: ASYNC240 for pure string os.path calls in async context
- Restore pre-commit if/else pattern in InlineSkillScript.run()
- Break long lines to fit 120-char limit in _skills.py and test_skills.py

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: collapse multi-line lambdas to single lines to fix pyright errors

The pyright ignore comments only suppress errors on the same line, so
multi-line lambdas left arguments on continuation lines uncovered.
Collapse both lambdas to single lines matching the existing load_skill
lambda pattern.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: replace untyped lambdas with typed inner functions to fix pyright errors

Python lambdas cannot have type annotations, so pyright reports
reportUnknownLambdaType and reportUnknownArgumentType errors that
cannot be suppressed with inline ignore comments. Replace the
lambdas for read_skill_resource and run_skill_script with typed
inner async functions.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: address PR review feedback on docs and prompt template

- Update with_prompt_template() docstring to document the
  {resource_instructions} placeholder requirement
- Remove stray backslashes after {resource_instructions} and
  {runner_instructions} in DEFAULT_SKILLS_INSTRUCTION_PROMPT
- Update subprocess_script_runner docstring to reflect
  FileSkillScript.full_path usage

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* refactor: replace dict[str, Skill] with Sequence[Skill] in SkillsProvider

Replace internal dict-based skills storage with Sequence[Skill] to
eliminate silent duplicate overwrites and simplify the code. Add
_find_skill helper for case-insensitive linear lookup.

Also fix pyright errors in tests by adding isinstance assertions
before accessing .function on SkillResource/SkillScript base types.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* refactor: add read-time resource path validation in _FileSkillsSource

Move security validation (path-traversal and symlink guards) for
file-based skill resources into _FileSkillsSource, restoring the
read-time checks that existed in main via _read_file_skill_resource.

- Add _get_validated_resource_path static method on _FileSkillsSource
  that validates containment, existence, and symlink safety
- _FileSkillsSource.get_skills() validates resource paths at discovery
  time via _get_validated_resource_path before passing to _FileSkillResource
- Move _normalize_resource_path, _is_path_within_directory, and
  _has_symlink_in_path from module-level into _FileSkillsSource as
  static methods (only used there)
- _FileSkillResource remains a simple path-to-content reader
- Add tests for _get_validated_resource_path security checks

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: reject str/Path in SkillsProvider constructor to prevent str-as-Sequence ambiguity

Since str is a Sequence, passing a path string to the source parameter
would silently be treated as a sequence of characters instead of a
file source. Add an explicit TypeError with a helpful message pointing
callers to SkillsProvider.from_paths().

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address PR #5584 review feedback

- Remove .NET reference from _FileSkillResource docstring
- Fix inconsistent resource name example (references/FAQ.md -> references/FAQ)
- Simplify SkillsProvider usage in code_defined_skill sample (pass single skill directly)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* remove skillsproviderbuilder

* Update python/packages/core/agent_framework/_skills.py

Co-authored-by: Eduard van Valkenburg <eavanvalkenburg@users.noreply.github.com>

* fix: remove dead code and fix sync function call in InlineSkillResource.read()

- Change await self.function() to self.function() for sync functions
  without **kwargs; async results are handled by inspect.isawaitable()
- Remove unreachable raise ValueError since __init__ already validates

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* remove full_path unnecessary property

* replace anyio with asyncio.to_thread for file I/O in _FileSkillResource

Replace anyio.Path usage with asyncio.to_thread + pathlib.Path since
anyio is not a direct dependency of core (transitive via mcp).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* simplify awaitable check to return directly

Use 'return await result' instead of assigning then returning.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* address PR review feedback for skills refactoring

- Replace anyio with asyncio.to_thread + pathlib.Path for file I/O
- Simplify awaitable check to return directly
- Remove unnecessary function None guard in InlineSkillResource.read()
- Add assert for type narrowing on self.function

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* address PR review feedback for skills refactoring

- Replace anyio with asyncio.to_thread + pathlib.Path for file I/O
- Simplify awaitable checks to return directly
- Remove unnecessary function None guard in InlineSkillResource.read()
- Use typing.cast instead of assert for type narrowing
- Add caching behavior note to SkillsProvider docstring

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* refactor: move name/description from abstract properties to Skill.__init__

Replace abstract properties for name and description on the Skill ABC
with a base __init__ that validates and stores them as regular
attributes. This simplifies custom Skill subclasses (only content
remains abstract) and centralizes validation in the base class,
consistent with SkillResource and SkillScript base classes.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Eduard van Valkenburg <eavanvalkenburg@users.noreply.github.com>
be8d2619e4 · 2026-05-06 09:45:06 +00:00
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Agent Skills Samples

These samples demonstrate how to use Agent Skills — modular packages of instructions, resources, and scripts that extend an agent's capabilities. Skills follow the Agent Skills specification and use progressive disclosure to optimize token usage.

Learning Path

Start with file-based or code-defined skills, then explore combining them and adding approval workflows.

Sample Description
file_based_skill Define skills as SKILL.md files on disk with reference documents and executable scripts. Uses the unit-converter skill.
code_defined_skill Define skills entirely in Python code using Skill, @skill.resource, and @skill.script decorators. Uses a code-defined unit-converter skill.
mixed_skills Combine code-defined and file-based skills in a single agent. Uses a code-defined volume-converter and a file-based unit-converter.
script_approval Require human-in-the-loop approval before executing skill scripts

Key Concepts

Progressive Disclosure

Skills use a three-step interaction model to minimize token usage:

  1. Advertise — Skill names and descriptions (~100 tokens each) are injected into the system prompt
  2. Load — Full instructions are loaded on-demand via the load_skill tool
  3. Access — Resources are read via read_skill_resource; scripts are executed via run_skill_script

File-Based vs Code-Defined Skills

Aspect File-Based Code-Defined
Definition SKILL.md files on disk Skill instances in Python
Resources Static files in references/ and assets/ directories Callable functions via @skill.resource decorator
Scripts Python files in scripts/ directory (executed via subprocess) Callable functions via @skill.script decorator (executed in-process)
Discovery Automatic via skill_paths parameter Explicit via skills parameter
Dynamic content No (static files only) Yes (functions can generate content at runtime)

Both types can be combined in a single SkillsProvider — see the mixed_skills sample.

Script Execution

Skills can include executable scripts. How a script runs depends on how it was defined:

Code-Defined Scripts File-Based Scripts
Defined via @skill.script decorator .py files in scripts/ directory
Execution In-process (direct function call) Delegated to a script_runner
script_runner needed? No — runs in-process automatically Yes — required

The script_runner parameter on SkillsProvider is only applicable to file-based scripts. Code-defined scripts are always executed in-process regardless of this setting. See file_based_skill for an example using a SkillScriptRunner callable with a subprocess runner, and code_defined_skill for in-process scripts that need no runner.

Prerequisites

All samples require:

  • An Azure AI Foundry project with a deployed model (e.g. gpt-4o-mini)
  • Azure CLI authentication (az login)
  • Environment variables set in a .env file (see python/.env.example)

Suppressing the experimental warning

The Agent Skills APIs in these samples are still experimental. Each sample includes a short commented warnings.filterwarnings(...) snippet near the imports. Uncomment it if you want to suppress the Skills warning before using the experimental APIs.