# Unknown errors when implementing FileReadTool

**URL:** <https://community.crewai.com/t/unknown-errors-when-implementing-filereadtool/7133>\
**Category:** CrewAI Community Support\
**Tags:** tools\_issues, crewai\
**Created:** [October 20, 2025, 4:13pm UTC](https://community.crewai.com/t/unknown-errors-when-implementing-filereadtool/7133 "2025-10-20T16:13:40Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![SamKablam](https://sea1.discourse-cdn.com/flex025/user_avatar/community.crewai.com/samkablam/32/2276_2.png) [@SamKablam](https://community.crewai.com/u/SamKablam)\
**Post date:** [October 20, 2025, 4:13pm UTC](https://community.crewai.com/t/unknown-errors-when-implementing-filereadtool/7133/1 "2025-10-20T16:13:40Z")

</div>

I am working on a project with an agent designed to read the text from a file and print to terminal (for now). I’ve gone through and set it up as I though it should based off the tutorials:

in Crew.py:  
`#initializing the tool:`  
`file_read_tool = FileReadTool(file_path='./tests/testFile.txt')`

`#adding the new agent that uses the tool:`  
`@agent def fileReadTool(self) -> Agent: return Agent( config=self.agents_config['fileReadTool'], # type: ignore[index] verbose=True, tools=file_read_tool )`

`I have also specified the Agent to use the file_read_tool.`

When I attempt to run it, I get a number of errors but don’t actually specify what is wrong:

```auto
Traceback (most recent call last):
File "...PycharmProjects/DetoxBot/detoxbot/src/detoxbot/main.py”, line 26, in run
Detoxbot().crew().kickoff(inputs=inputs)
~~~~~~~~ ^^
File “...PycharmProjects/DetoxBot/detoxbot/.venv/lib/python3.13/site-packages/crewai/project/crew_base.py”, line 39, in init
self.map_all_agent_variables()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^^
File “...PycharmProjects/DetoxBot/detoxbot/.venv/lib/python3.13/site-packages/crewai/project/crew_base.py”, line 181, in map_all_agent_variables
self._map_agent_variables(
~~~~~~~~~~~~~~~~~~~~~~~~~ ^
agent_name,
^^^^^^^^^^^
…<4 lines>…
callbacks,
^^^^^^^^^^
)
^
File “...PycharmProjects/DetoxBot/detoxbot/.venv/lib/python3.13/site-packages/crewai/project/crew_base.py”, line 207, in _map_agent_variables
tool_functionstool for tool in tools
~~~~~~~~~~~~~~ ^^^^^^
KeyError: ‘f’

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “...PycharmProjects/DetoxBot/detoxbot/.venv/bin/run_crew”, line 10, in 
sys.exit(run())
~~~^^
File “...PycharmProjects/DetoxBot/detoxbot/src/detoxbot/main.py”, line 28, in run
raise Exception(f"An error occurred while running the crew: {e}")
Exception: An error occurred while running the crew: ‘f’
An error occurred while running the crew: Command ‘[‘uv’, ‘run’, ‘run_crew’]’ returned non-zero exit status 1.

```

Any suggestions about what I can check to ensure using tools isn’t throwing an error?

---

<div class="post-metadata">

**Author:** ![carmelo\_iaria](https://sea1.discourse-cdn.com/flex025/user_avatar/community.crewai.com/carmelo_iaria/32/4432_2.png) [@carmelo\_iaria](https://community.crewai.com/u/carmelo_iaria)\
**Post date:** [October 24, 2025, 11:10pm UTC](https://community.crewai.com/t/unknown-errors-when-implementing-filereadtool/7133/2 "2025-10-24T23:10:44Z")

</div>

The error you’re encountering is a common issue with CrewAI when passing tools to agents. The problem is in how you’re passing the tool to the agent.

## The Issue

In your code you have

```auto
tools=file_read_tool

```

You’re passing a **single tool instance** directly, but CrewAI expects tools to be passed as a **list** (even if there’s only one tool).

The `KeyError: 'f'` happens because CrewAI tries to iterate over what it thinks is a collection of tools, but instead it’s iterating over the characters of the tool object’s string representation.

## The Solution

Change your agent definition to wrap the tool in a list:

python

```auto
@agent
def fileReadTool(self) -> Agent:
    return Agent(
        config=self.agents_config['fileReadTool'],
        verbose=True,
        tools=[file_read_tool] # ← Wrap in a list!
    )

```

Try making that change and the error should be resolved! Let me know if you encounter any other issues.

---

<div class="post-metadata">

**Author:** ![SamKablam](https://sea1.discourse-cdn.com/flex025/user_avatar/community.crewai.com/samkablam/32/2276_2.png) [@SamKablam](https://community.crewai.com/u/SamKablam)\
**Post date:** [October 25, 2025, 12:31am UTC](https://community.crewai.com/t/unknown-errors-when-implementing-filereadtool/7133/3 "2025-10-25T00:31:31Z")

</div>

> [@carmelo\_iaria](#):
>
> `tools=[file_read_tool]`

Ok, so while I was looking for a solution I re-setup the project, but I tried your solution:

```python
#crew.py
from crewai_tools import FileReadTool

#initiate tool
fileRead = FileReadTool()

@agent
    def debugAgent(self) -> Agent:
        return Agent(
            config=self.agents_config['debugAgent'], # type: ignore[index]
            verbose=True,
            tools=[fileRead]
        )

@task
    def debug_task(self) -> Task:
        logging.debug("Creating debug_task")
        try:
            return Task(
                config=self.tasks_config['debug_task'], # type: ignore[index]
                output_file='report.md'
            )
        except Exception as e:
            logging.error(f"Error while creating debug_task: {e}")
            raise

#agents.yaml
debugAgent:
  role: >
    [role text]
  goal: >
    [goal text]
  backstory: >
    [backstory text]
  tools: >
    [fileRead]

```

I’m still getting errors, but now I’m getting:  
`Exception: An error occurred while running the crew: ‘[’` so I think I’m still missing a [] wrapper somewhere? Thanks!

---

<div class="post-metadata">

**Author:** ![carmelo\_iaria](https://sea1.discourse-cdn.com/flex025/user_avatar/community.crewai.com/carmelo_iaria/32/4432_2.png) [@carmelo\_iaria](https://community.crewai.com/u/carmelo_iaria)\
**Post date:** [October 25, 2025, 12:59am UTC](https://community.crewai.com/t/unknown-errors-when-implementing-filereadtool/7133/4 "2025-10-25T00:59:53Z")

</div>

The problem is in your **`agents.yaml`** file. You don’t need to (and shouldn’t) specify tools in the YAML config file when you’re already passing them programmatically in the Python code.

Pass tools in your Python code (what you’re doing now):

```auto
# crew.py
from crewai_tools import FileReadTool

fileRead = FileReadTool()

@agent
def debugAgent(self) -> Agent:
    return Agent(
        config=self.agents_config['debugAgent'],
        verbose=True,
        tools=[fileRead] # ← Tools here
    )

```

but not in the yaml file

```auto
# agents.yaml
debugAgent:
  role: >
    Debug Agent
  goal: >
    Read and analyze files
  backstory: >
    You are an expert at debugging
  # NO tools key here!

```

---

<div class="post-metadata">

**Author:** ![SamKablam](https://sea1.discourse-cdn.com/flex025/user_avatar/community.crewai.com/samkablam/32/2276_2.png) [@SamKablam](https://community.crewai.com/u/SamKablam)\
**Post date:** [October 25, 2025, 3:05am UTC](https://community.crewai.com/t/unknown-errors-when-implementing-filereadtool/7133/5 "2025-10-25T03:05:20Z")

</div>

That fixed it, finally! Thank you!!

---

<div class="post-metadata">

**Author:** ![Lorenze\_Jay](https://sea1.discourse-cdn.com/flex025/user_avatar/community.crewai.com/lorenze_jay/32/637_2.png) [@Lorenze\_Jay](https://community.crewai.com/u/Lorenze_Jay)\
**Post date:** [October 28, 2025, 12:34am UTC](https://community.crewai.com/t/unknown-errors-when-implementing-filereadtool/7133/6 "2025-10-28T00:34:58Z")

</div>

Great suggestions: **[carmelo\_iaria](https://community.crewai.com/u/carmelo_iaria) ! Happy to hear you got everything working** @SamKablam