| name | alfworld-task-verifier |
| description | Use when the agent needs to check whether an ALFWorld task objective has been met after completing a sub-action (e.g., placing an object). This skill parses the task goal, evaluates the latest environment observation, and outputs a verification decision — task complete, task incomplete, or action ineffective — to guide the next step. |
Skill: Task Verifier for ALFWorld
When to Use
Trigger this skill when:
- The agent has just completed a key sub-action (e.g.,
put {obj} in/on {recep})
- The agent needs to determine whether the overall task goal is satisfied
- 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.
