
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
In the rectangular coordinate system $(xoy)$, with $O$ as the pole and the positive semi-axis of $x$ as the polar axis, a polar coordinate system is established with the same unit length. Given that the parametric equations of curve $C_{1}$ are $ \begin{cases} x= \sqrt {3}+2\cos \alpha \\ y=3+2\sin \alpha \end{cases} $ $(\alpha \in [0,2\pi]$, $\alpha$ is the parameter$)$, and the polar coordinate equation of curve $C_{2}$ is $\rho \sin (\theta + \frac{\pi}{3})=a$ $(a \in \mathbb{R})$. If curves $C_{1}$ and $C_{2}$ have exactly one common point, find the value of the real number $a$.

Present the answer in LaTex format: \boxed{Your answer}
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