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Base

base

AXM Tool interface — structural protocol for deterministic tools.

Tools are the deterministic execution layer of the AXM architecture. The LLM agent decides WHEN to invoke a tool (probabilistic decision), but the tool itself executes deterministically.

Architecture

Agent (probabilistic) → orchestrator.run_tool() → AXMTool.execute() (deterministic)

Discovery

Tools are auto-discovered via entry points (group axm.tools). Each tool defines its own execute() signature with explicit, typed parameters — the MCP discovery layer introspects these to generate JSON-Schema automatically.

AXMTool

Bases: Protocol

Structural protocol for AXM deterministic tools.

Implementors must provide: - name (property): unique tool identifier - execute(...) : deterministic execution with explicit params

Optionally provide: - agent_hint (class attribute): optional, free-form one-liner optimized for LLM consumption: what the tool does, key params, and what it replaces. Like the other discovery attributes below, it is not a protocol member and carries no guaranteed fallback — some discovery tooling reads it best-effort via getattr / :func:tool_metadata; absent, nothing is substituted. - expose_directly (class attribute, default False): when True, the MCP server registers this tool directly in tools/list (the hot path). When False (default), the tool is reachable only through the MCP facade (axm_search -> axm_describe -> axm_call), keeping the tools/list payload small. - domain (class attribute, default None): coarse capability group used by the facade for axm_capabilities and to scope axm_search (e.g. "ast", "git", "ticket"). - tags (class attribute, default frozenset()): free-form keywords feeding facade discovery (axm_search).

Uses structural typing (PEP 544) — no inheritance required. @runtime_checkable enables isinstance() checks. The discovery attributes (expose_directly / domain / tags) are not protocol members on purpose: adding data attributes to a runtime_checkable protocol would make them required for isinstance() and break the check for the many tools that satisfy AXMTool structurally without subclassing it. Read them through :func:tool_metadata (or getattr(tool, name, default)) instead, which works for subclasses and structural tools alike.

Example::

Text Only
class MyTool(AXMTool):
    agent_hint = "Frobnicate widgets — use width param."
    expose_directly = True          # hot path (read via tool_metadata)
    domain = "widget"
    tags = frozenset({"frobnicate"})

    @property
    def name(self) -> str:
        return "my-tool"

    def execute(self, *, value: int = 0) -> ToolResult:
        return ToolResult(success=True, data={"result": value})
Source code in packages/axm/src/axm/tools/base.py
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@runtime_checkable
class AXMTool(Protocol):
    """Structural protocol for AXM deterministic tools.

    Implementors must provide:
    - ``name`` (property): unique tool identifier
    - ``execute(...)`` : deterministic execution with explicit params

    Optionally provide:
    - ``agent_hint`` (class attribute): optional, free-form one-liner
      optimized for LLM consumption: what the tool does, key params, and
      what it replaces.  Like the other discovery attributes below, it is
      *not* a protocol member and carries no guaranteed fallback — some
      discovery tooling reads it best-effort via ``getattr`` /
      :func:`tool_metadata`; absent, nothing is substituted.
    - ``expose_directly`` (class attribute, default ``False``): when
      ``True``, the MCP server registers this tool directly in
      ``tools/list`` (the *hot path*).  When ``False`` (default), the
      tool is reachable only through the MCP facade
      (``axm_search`` -> ``axm_describe`` -> ``axm_call``), keeping the
      ``tools/list`` payload small.
    - ``domain`` (class attribute, default ``None``): coarse capability
      group used by the facade for ``axm_capabilities`` and to scope
      ``axm_search`` (e.g. ``"ast"``, ``"git"``, ``"ticket"``).
    - ``tags`` (class attribute, default ``frozenset()``): free-form
      keywords feeding facade discovery (``axm_search``).

    Uses structural typing (PEP 544) — no inheritance required.
    ``@runtime_checkable`` enables ``isinstance()`` checks.  The discovery
    attributes (``expose_directly`` / ``domain`` / ``tags``) are *not*
    protocol members on purpose: adding data attributes to a
    ``runtime_checkable`` protocol would make them required for
    ``isinstance()`` and break the check for the many tools that satisfy
    ``AXMTool`` structurally without subclassing it.  Read them through
    :func:`tool_metadata` (or ``getattr(tool, name, default)``) instead,
    which works for subclasses and structural tools alike.

    Example::

        class MyTool(AXMTool):
            agent_hint = "Frobnicate widgets — use width param."
            expose_directly = True          # hot path (read via tool_metadata)
            domain = "widget"
            tags = frozenset({"frobnicate"})

            @property
            def name(self) -> str:
                return "my-tool"

            def execute(self, *, value: int = 0) -> ToolResult:
                return ToolResult(success=True, data={"result": value})
    """

    @property
    def name(self) -> str:
        """Unique tool identifier (e.g., 'esbmc', 'dafny', 'pytest')."""
        ...

    def execute(self, **kwargs: Any) -> ToolResult:
        """Execute the tool with given arguments.

        Subclasses should override with explicit, typed parameters::

            def execute(self, *, title: str = "", body: str = "") -> ToolResult:
                ...

        The ``**kwargs`` signature here is the *structural minimum* —
        any callable accepting keyword arguments satisfies it.

        Returns:
            ToolResult with success status and structured data.
        """
        ...
name property

Unique tool identifier (e.g., 'esbmc', 'dafny', 'pytest').

execute(**kwargs)

Execute the tool with given arguments.

Subclasses should override with explicit, typed parameters::

Text Only
def execute(self, *, title: str = "", body: str = "") -> ToolResult:
    ...

The **kwargs signature here is the structural minimum — any callable accepting keyword arguments satisfies it.

Returns:

Type Description
ToolResult

ToolResult with success status and structured data.
Source code in packages/axm/src/axm/tools/base.py
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def execute(self, **kwargs: Any) -> ToolResult:
    """Execute the tool with given arguments.

    Subclasses should override with explicit, typed parameters::

        def execute(self, *, title: str = "", body: str = "") -> ToolResult:
            ...

    The ``**kwargs`` signature here is the *structural minimum* —
    any callable accepting keyword arguments satisfies it.

    Returns:
        ToolResult with success status and structured data.
    """
    ...

ToolMetadata dataclass

Facade/CLI discovery metadata for a tool, with safe defaults.

Built by :func:tool_metadata from the optional expose_directly / domain / tags attributes a tool may declare. Centralising the defaults here keeps the MCP facade and the CLI reading the same contract.

Attributes:

Name Type Description
expose_directly bool

Whether the tool is on the MCP hot path (registered directly in tools/list). Default False.
domain str | None

Coarse capability group, or None if ungrouped.
tags frozenset[str]

Discovery keywords (possibly empty).
Source code in packages/axm/src/axm/tools/base.py
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@dataclass(frozen=True)
class ToolMetadata:
    """Facade/CLI discovery metadata for a tool, with safe defaults.

    Built by :func:`tool_metadata` from the optional ``expose_directly`` /
    ``domain`` / ``tags`` attributes a tool may declare.  Centralising the
    defaults here keeps the MCP facade and the CLI reading the same contract.

    Attributes:
        expose_directly: Whether the tool is on the MCP hot path
            (registered directly in ``tools/list``).  Default ``False``.
        domain: Coarse capability group, or ``None`` if ungrouped.
        tags: Discovery keywords (possibly empty).
    """

    expose_directly: bool = False
    domain: str | None = None
    tags: frozenset[str] = frozenset()

ToolResult dataclass

Immutable result of a tool execution.

Attributes:

Name Type Description
success bool

Whether the tool execution succeeded.
data dict[str, Any]

Structured output data (backend-specific).
error str | None

Human-readable error message, if any.
hint str | None

Optional next-step suggestion for the agent.
text str | None

Optional pre-rendered text representation (e.g. Markdown).
Source code in packages/axm/src/axm/tools/base.py
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@dataclass(frozen=True)
class ToolResult:
    """Immutable result of a tool execution.

    Attributes:
        success: Whether the tool execution succeeded.
        data: Structured output data (backend-specific).
        error: Human-readable error message, if any.
        hint: Optional next-step suggestion for the agent.
        text: Optional pre-rendered text representation (e.g. Markdown).
    """

    success: bool
    data: dict[str, Any] = field(default_factory=dict)
    error: str | None = None
    hint: str | None = None
    text: str | None = None

tool_metadata(tool)

Read a tool's optional discovery attributes into a :class:ToolMetadata.

Works for tools that subclass :class:AXMTool, tools that satisfy it structurally, and plain callables — anything missing an attribute falls back to the default. tags is coerced to a frozenset so callers can rely on set semantics regardless of how the tool declared it.

Parameters:

Name Type Description Default
tool object

The tool instance (or plain callable) to introspect.

 required

Returns:

Name Type Description
A ToolMetadata

class:ToolMetadata with resolved values.
Source code in packages/axm/src/axm/tools/base.py
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def tool_metadata(tool: object) -> ToolMetadata:
    """Read a tool's optional discovery attributes into a :class:`ToolMetadata`.

    Works for tools that subclass :class:`AXMTool`, tools that satisfy it
    structurally, and plain callables — anything missing an attribute falls
    back to the default.  ``tags`` is coerced to a ``frozenset`` so callers
    can rely on set semantics regardless of how the tool declared it.

    Args:
        tool: The tool instance (or plain callable) to introspect.

    Returns:
        A :class:`ToolMetadata` with resolved values.
    """
    raw_tags = getattr(tool, "tags", None) or ()
    return ToolMetadata(
        expose_directly=bool(getattr(tool, "expose_directly", False)),
        domain=getattr(tool, "domain", None),
        tags=frozenset(raw_tags),
    )