alfworld-task-verifier

Skill: Task Verifier for ALFWorld

When to Use

Trigger this skill when:

1. The agent has just completed a key sub-action (e.g., put {obj} in/on {recep})
2. The agent needs to determine whether the overall task goal is satisfied
3. The agent must decide whether to continue searching or conclude the task

Core Workflow

1. Parse the Task Goal

Extract from the original task description:

• Target object(s): What needs to be found/placed (including quantity)
• Target receptacle: Where objects must end up
• Required transformations: Any cleaning, heating, or cooling steps

2. Analyze the Observation

Evaluate the most recent Observation: text from the environment:

• Look for evidence that required objects are present in the target receptacle
• Count how many target objects have been successfully placed
• Note: Other items in the receptacle do not invalidate success

3. Make a Verification Decision

| Condition | Decision | Output |

|-----------|----------|--------|

| All required objects confirmed in target receptacle | Complete | Verification: Task complete. No further action needed. |

| Some but not all objects placed | Incomplete | Verification: Task incomplete. Continue searching for {missing object(s)}. |

| Observation says "Nothing happened" | Ineffective | Verification: Last action was ineffective. Re-assess and try a different approach. |

| Object placed in wrong receptacle | Incorrect | Verification: Object placed in wrong location. Retrieve and redirect to {correct receptacle}. |

4. Output Format

Output only the verification decision. Do not output the next action. This skill informs the planning for the next step, not the execution.

Example

Task: "Find two pen and put them in garbagecan."

Action: put pen 3 in/on garbagecan 1
Observation: You put the pen 3 in/on the garbagecan 1.

> Verification: Task incomplete. Continue searching for pen (1 of 2 placed).

Action: put pen 1 in/on garbagecan 1
Observation: You put the pen 1 in/on the garbagecan 1.

> Verification: Task complete. No further action needed.

Example — Failed action:

Action: put pen 3 in/on garbagecan 1
Observation: Nothing happened.

> Verification: Last action was ineffective. Re-assess and try a different approach.

Error Handling

• Ambiguous observation: If the observation does not clearly confirm or deny placement, navigate to the target receptacle and re-examine it to get an updated state.
• Quantity tracking: For multi-object tasks, maintain a running count. Re-examine the target receptacle if the count is uncertain.