Parent Standard: Harness Architecture Standard
Parent Architecture: Execution Layer — Enforcement Standard
Category: Governance & Enforcement
Subcategory: Tool Access Control
Type: Execution Containment Module
Version: 1.0
Status: Canonical · Open Module
Effective Date: 9 May 2026
Compatibility: OOF® Methodology OS™ · Harness Architecture Standard ·
Execution Layer — Enforcement Standard · RIS · INTEGROS® · OGL™ · ART · OIB™
Authority: OOF®
Protection: MIP® — Methodological Intellectual Property
Canonical Language: English (UCL™)

Canonical Definition

Tool Access Control Module defines the structural conditions under
which a system may access, invoke, restrict, sequence, or deny tools,
interfaces, functions, or execution-capable resources within a
contained execution environment.

A system satisfies TACM only if:

• tool access is explicitly defined
• available and unavailable tools are distinguishable
• invocation conditions remain bounded by governed rules
• unauthorized or out-of-scope tool use is restricted
• tool access does not silently expand through delegation, runtime change, or indirect execution paths

A system that can invoke tools without governed access conditions does
not satisfy TACM.

Module Function

TACM defines the controlled tool-access layer of execution containment.

It ensures that tools are not treated as neutral capabilities available
by default, but as governed execution surfaces that must remain bounded,
permission-linked, and operationally restricted.

The module applies wherever autonomous systems may call:

• tools
• APIs
• execution functions
• filesystems
• code runtimes
• external services
• command environments
• action-triggering interfaces

Minimum Implementation Framework (MIF)

Step 1 — Define the Tool Surface

The organization must define which tools or execution-capable interfaces
exist within the contained environment.

Minimum requirement:

• tool classes are explicit
• executable and non-executable interfaces are distinguishable
• undefined tool surfaces are excluded from valid operation

Step 2 — Define Access Eligibility

The system must define who or what may access each tool.

Minimum requirement:

• tool eligibility is explicit
• valid callers are identifiable
• unauthorized entities are excluded from valid tool invocation

Step 3 — Define Invocation Conditions

The system must define under what conditions a tool may be invoked.

Minimum requirement:

• invocation triggers are explicit
• tool use is not open-ended by default
• context-free or unrestricted invocation is excluded from valid access logic

Step 4 — Define Restriction and Denial Logic

The system must define how tool access is limited, denied, or escalated.

Minimum requirement:

• restricted and prohibited tool conditions are explicit
• denial logic is enforceable
• silent expansion of access is excluded from valid containment

Step 5 — Preserve Tool Access Traceability

The system must preserve visibility of who invoked what, when, under
which condition, and through which path.

Minimum requirement:

• tool invocation path is traceable
• later review can reconstruct access history
• indirect or chained tool access remains visible

Step 6 — Restrict Invalid Tool Use

The system must not be treated as valid if tools are invoked outside
governed scope, through hidden access paths, or without explicit bounded
conditions.

Minimum requirement:

• invalid tool access conditions are identifiable
• unauthorized or out-of-scope invocation is blocked or invalidated
• execution convenience does not override tool-access governance

Use Case 1 — AI Agent with Mixed Tool Surface

Scenario

An AI agent operates inside a contained environment with access to
selected tools, but must not invoke external functions or higher-impact
tools outside approved scope.

Application

TACM is used to ensure:

• available tools are explicitly defined
• only valid callers may invoke them
• access conditions remain bounded
• unauthorized tool expansion is blocked

Result

The organization gains a stronger basis for preventing authorized
execution from turning into uncontrolled tool use.

Use Case 2 — Enterprise Automation with Sensitive Interfaces

Scenario

A system may interact with documents, internal APIs, workflow triggers,
or external services, but only under specific operational and
containment conditions.

Application

TACM is used to ensure:

• tool surface is governed
• invocation conditions are explicit
• denial and restriction logic remain enforceable
• access history is traceable across the contained environment

Result

The organization gains a structurally governed tool-access layer instead
of relying on assumed good behavior inside an execution environment.

Canonical Closing Statement

If tool access is not governed, execution containment does not
exist.

→ Harness Architecture Standard