Transformers Agent suggesting it should use text_generator although it is not provided.
Author: tordbb
Pull request: no

### System Info

I am running a version of  [your notebook on Transformers Agent](https://colab.research.google.com/drive/1c7MHD-T1forUPGcC_jlwsIptOzpG3hSj), where I have added a cell where I ask the StarCoder agent to generate a sentence for me. 

I am using StarCoder, as you can see:
```
#@title Agent init
agent_name = "StarCoder (HF Token)" #@param ["StarCoder (HF Token)", "OpenAssistant (HF Token)", "OpenAI (API Key)"]

import getpass

if agent_name == "StarCoder (HF Token)":
    from transformers.tools import HfAgent
    agent = HfAgent("https://api-inference.huggingface.co/models/bigcode/starcoder")
    print("StarCoder is initialized 💪")
elif agent_name == "OpenAssistant (HF Token)":
    from transformers.tools import HfAgent
    agent = HfAgent(url_endpoint="https://api-inference.huggingface.co/models/OpenAssistant/oasst-sft-4-pythia-12b-epoch-3.5")
    print("OpenAssistant is initialized 💪")
if agent_name == "OpenAI (API Key)":
    from transformers.tools import OpenAiAgent
    pswd = getpass.getpass('OpenAI API key:')
    agent = OpenAiAgent(model="text-davinci-003", api_key=pswd)
    print("OpenAI is initialized 💪")
```

### Who can help?

 @ArthurZucker and @younesbelkada

### Information

- [ ] The official example scripts
- [X] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [X] My own task or dataset (give details below)

### Reproduction

Based on the notebook mentioned, I have added a cell where I prompt the following:
```
agent.run("Write a sentence of the form 'A_ V_ at P_', where A_ should be replaced by the name of an animal, V_ should be replaced by a verb, and P_ should be replaced by the name of a place. Examples for valid sentences are 'Dog eating at macdonalds', 'Horse jumping at a gym', 'Duck fishing at a supermarket'. ")
```

As you see in the printout below, it suggests it will use the tool 'text_generation', but then stops because it does not have access to it. 


```
==Explanation from the agent==
I will use the following  tools: `text_classifier` to classify the sentence, then `text_generator` to generate the sentence.


==Code generated by the agent==
sentence = text_generator(prompt="A_ V_ at P_")
print(f"The sentence is {sentence}.")
sentence_class = text_classifier(sentence)
print(f"The sentence class is {sentence_class}.")


==Result==
Evaluation of the code stopped at line 0 before the end because of the following error:
It is not permitted to evaluate other functions than the provided tools (tried to execute text_generator).
```


### Expected behavior

Either, the agent should not even consider using "text_generation" as a tool, or it should have access to this tool as default.


Comments:
I'm not too sure why you are reporting a bug. The agent is an LLM which sometimes hallucinate content (in this case, a tool that does not exist). If your prompt does not work, you should try refining it. You should also try using another model and see if it performs better.

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.