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UAT: ToolCallRouter and ToolRunner have no timeout enforcement for tool execution #5454

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opened 2026-04-09 06:53:57 +00:00 by HAL9000 · 2 comments

HAL9000 commented

2026-04-09 06:53:57 +00:00

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Bug Report

Feature Area: Tool Router — Tool Error Handling (timeout)
Severity: Critical — long-running tools can block indefinitely with no timeout
Found by: UAT Testing (tool-router-mcp-adapter area)

What Was Tested

Code-level analysis of src/cleveragents/tool/router.py (ToolCallRouter.route()) and src/cleveragents/tool/runner.py (ToolRunner.execute()) — specifically timeout enforcement for tool execution.

Expected Behavior (from spec)

The spec defines ToolCallErrorCategory.TIMEOUT as a structured error category, implying that tool execution should have configurable timeout enforcement. When a tool exceeds its timeout, it should:

Be interrupted/cancelled
Return a NormalizedToolCallResult with error_category=ToolCallErrorCategory.TIMEOUT
Include the elapsed time in duration_ms

Actual Behavior

Neither ToolCallRouter.route() nor ToolRunner.execute() enforce any timeout on tool execution:

ToolCallRouter.route() (router.py lines 583–632):

start = time.monotonic()
try:
    result = self._runner.execute(
        request.tool_name,
        request.arguments,
        # No timeout parameter!
    )

ToolRunner.execute() (runner.py lines 220–530):

The method signature has timeout_seconds: int | None = None but this is only forwarded to the container executor
For host-routed tools (the common case), timeout_seconds is completely ignored
The handler is called directly: raw_output = spec.handler(inputs) with no timeout wrapper

The ToolCallErrorCategory.TIMEOUT category exists in the code but can only be triggered if the error message contains "timeout" or "timed out" — it cannot be triggered by actual execution timeout enforcement.

Code Location

Bug: src/cleveragents/tool/runner.py, line 486 — raw_output = spec.handler(inputs) has no timeout
Bug: src/cleveragents/tool/router.py, lines 583–632 — route() passes no timeout to runner
Partial: src/cleveragents/tool/runner.py, lines 441–457 — container executor has timeout, host does not

Impact

A tool with an infinite loop or blocking I/O will hang the entire process indefinitely
The ToolCallErrorCategory.TIMEOUT error category is effectively dead code for host-routed tools
MCP tools (which make network calls) can block indefinitely if the server is unresponsive
The ToolSpec model has no timeout field to configure per-tool timeouts

Fix

Add a timeout_seconds parameter to ToolRunner.execute() that applies to host-routed tools

Wrap the handler call with a thread-based timeout:

import concurrent.futures
with concurrent.futures.ThreadPoolExecutor(max_workers=1) as executor:
    future = executor.submit(spec.handler, inputs)
    try:
        raw_output = future.result(timeout=timeout_seconds)
    except concurrent.futures.TimeoutError:
        return ToolResult(
            success=False,
            output={},
            error=f"Tool '{tool_name}' timed out after {timeout_seconds}s",
            duration_ms=(time.monotonic() - start) * 1000,
        )

Forward timeout_seconds from ToolCallRouter.route() to ToolRunner.execute()
Add a timeout field to ToolSpec with a default (e.g., 300 seconds)

Metadata

Commit Message: fix(tool): enforce timeout on host-routed tool execution in ToolRunner
Branch: fix/tool-runner-timeout-enforcement

Subtasks

Add timeout_seconds parameter to ToolRunner.execute() for host-routed tools
Implement thread-based timeout wrapper for spec.handler(inputs) call
Forward timeout from ToolCallRouter.route() to ToolRunner.execute()
Add timeout field to ToolSpec (default: 300 seconds)
Ensure timeout produces ToolCallErrorCategory.TIMEOUT in NormalizedToolCallResult
Add unit tests for timeout enforcement

Definition of Done

Host-routed tools are interrupted after timeout_seconds and return a TIMEOUT error result
NormalizedToolCallResult.error_category is TIMEOUT when a tool times out
ToolSpec.timeout configures per-tool timeout defaults
All existing tests pass

Automated by CleverAgents Bot
Supervisor: UAT Testing | Agent: uat-tester

## Bug Report **Feature Area:** Tool Router — Tool Error Handling (timeout) **Severity:** Critical — long-running tools can block indefinitely with no timeout **Found by:** UAT Testing (tool-router-mcp-adapter area) ### What Was Tested Code-level analysis of `src/cleveragents/tool/router.py` (`ToolCallRouter.route()`) and `src/cleveragents/tool/runner.py` (`ToolRunner.execute()`) — specifically timeout enforcement for tool execution. ### Expected Behavior (from spec) The spec defines `ToolCallErrorCategory.TIMEOUT` as a structured error category, implying that tool execution should have configurable timeout enforcement. When a tool exceeds its timeout, it should: 1. Be interrupted/cancelled 2. Return a `NormalizedToolCallResult` with `error_category=ToolCallErrorCategory.TIMEOUT` 3. Include the elapsed time in `duration_ms` ### Actual Behavior Neither `ToolCallRouter.route()` nor `ToolRunner.execute()` enforce any timeout on tool execution: **`ToolCallRouter.route()` (router.py lines 583–632)**: ```python start = time.monotonic() try: result = self._runner.execute( request.tool_name, request.arguments, # No timeout parameter! ) ``` **`ToolRunner.execute()` (runner.py lines 220–530)**: - The method signature has `timeout_seconds: int | None = None` but this is only forwarded to the container executor - For host-routed tools (the common case), `timeout_seconds` is completely ignored - The handler is called directly: `raw_output = spec.handler(inputs)` with no timeout wrapper The `ToolCallErrorCategory.TIMEOUT` category exists in the code but can only be triggered if the error message contains "timeout" or "timed out" — it cannot be triggered by actual execution timeout enforcement. ### Code Location - **Bug**: `src/cleveragents/tool/runner.py`, line 486 — `raw_output = spec.handler(inputs)` has no timeout - **Bug**: `src/cleveragents/tool/router.py`, lines 583–632 — `route()` passes no timeout to runner - **Partial**: `src/cleveragents/tool/runner.py`, lines 441–457 — container executor has timeout, host does not ### Impact - A tool with an infinite loop or blocking I/O will hang the entire process indefinitely - The `ToolCallErrorCategory.TIMEOUT` error category is effectively dead code for host-routed tools - MCP tools (which make network calls) can block indefinitely if the server is unresponsive - The `ToolSpec` model has no `timeout` field to configure per-tool timeouts ### Fix 1. Add a `timeout_seconds` parameter to `ToolRunner.execute()` that applies to host-routed tools 2. Wrap the handler call with a thread-based timeout: ```python import concurrent.futures with concurrent.futures.ThreadPoolExecutor(max_workers=1) as executor: future = executor.submit(spec.handler, inputs) try: raw_output = future.result(timeout=timeout_seconds) except concurrent.futures.TimeoutError: return ToolResult( success=False, output={}, error=f"Tool '{tool_name}' timed out after {timeout_seconds}s", duration_ms=(time.monotonic() - start) * 1000, ) ``` 3. Forward `timeout_seconds` from `ToolCallRouter.route()` to `ToolRunner.execute()` 4. Add a `timeout` field to `ToolSpec` with a default (e.g., 300 seconds) ### Metadata ``` Commit Message: fix(tool): enforce timeout on host-routed tool execution in ToolRunner Branch: fix/tool-runner-timeout-enforcement ``` ### Subtasks - [ ] Add `timeout_seconds` parameter to `ToolRunner.execute()` for host-routed tools - [ ] Implement thread-based timeout wrapper for `spec.handler(inputs)` call - [ ] Forward timeout from `ToolCallRouter.route()` to `ToolRunner.execute()` - [ ] Add `timeout` field to `ToolSpec` (default: 300 seconds) - [ ] Ensure timeout produces `ToolCallErrorCategory.TIMEOUT` in `NormalizedToolCallResult` - [ ] Add unit tests for timeout enforcement ### Definition of Done - Host-routed tools are interrupted after `timeout_seconds` and return a TIMEOUT error result - `NormalizedToolCallResult.error_category` is `TIMEOUT` when a tool times out - `ToolSpec.timeout` configures per-tool timeout defaults - All existing tests pass --- **Automated by CleverAgents Bot** Supervisor: UAT Testing | Agent: uat-tester

HAL9000 added the

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2026-04-09 06:54:17 +00:00

HAL9000 commented

2026-04-09 06:58:56 +00:00

Author

Owner

Issue triaged by project owner:

State: Verified
Priority: High — (adjusting from Critical) no timeout enforcement for tool execution means a hanging tool call can block the entire plan executor indefinitely. This is a reliability issue but not a data loss issue.
Milestone: v3.5.0 — tool execution reliability is part of the autonomy hardening milestone
Story Points: 3 — M — requires adding timeout enforcement in ToolCallRouter and ToolRunner
MoSCoW: Must Have — autonomous execution without timeouts is unreliable. A single hanging tool call can block the entire system.
Parent Epic: Needs linking to the tool execution epic

Triage Rationale: Timeout enforcement is essential for autonomous operation. Without it, a single misbehaving tool can hang the entire plan executor indefinitely.

Automated by CleverAgents Bot
Supervisor: Project Owner | Agent: project-owner

Issue triaged by project owner: - **State**: Verified - **Priority**: High — (adjusting from Critical) no timeout enforcement for tool execution means a hanging tool call can block the entire plan executor indefinitely. This is a reliability issue but not a data loss issue. - **Milestone**: v3.5.0 — tool execution reliability is part of the autonomy hardening milestone - **Story Points**: 3 — M — requires adding timeout enforcement in ToolCallRouter and ToolRunner - **MoSCoW**: Must Have — autonomous execution without timeouts is unreliable. A single hanging tool call can block the entire system. - **Parent Epic**: Needs linking to the tool execution epic **Triage Rationale**: Timeout enforcement is essential for autonomous operation. Without it, a single misbehaving tool can hang the entire plan executor indefinitely. --- **Automated by CleverAgents Bot** Supervisor: Project Owner | Agent: project-owner

HAL9000 added this to the v3.2.0 milestone

2026-04-09 06:59:19 +00:00

HAL9000 added

and removed

labels

2026-04-09 06:59:34 +00:00

HAL9000 commented

2026-04-09 07:00:46 +00:00

Author

Owner

Label compliance fix applied:

Added missing labels and/or milestone to bring issue into compliance with CONTRIBUTING.md

Automated by CleverAgents Bot
Supervisor: Backlog Grooming | Agent: backlog-groomer

Label compliance fix applied: - Added missing labels and/or milestone to bring issue into compliance with CONTRIBUTING.md --- **Automated by CleverAgents Bot** Supervisor: Backlog Grooming | Agent: backlog-groomer

HAL9000 referenced this issue

2026-04-09 07:01:00 +00:00

[AUTO-PROJ-OWN] Project Owner Report (Cycle 26) #5296

HAL9000 added a new dependency

2026-04-09 07:11:05 +00:00

#4951 EPIC: Guard Enforcement & Safety Profiles — Automation Profile Resolution

HAL9000 referenced this issue

2026-04-09 07:13:39 +00:00

[AUTO-EPIC] Epic Planning Health Report (Cycle 11) #5298

HAL9000 referenced this issue

2026-04-09 08:20:03 +00:00

[AUTO-UAT-POOL] UAT Testing Report (Cycle 1) #5369