Supreme Law Library : References : Bouvier's Law Dictionary : bldl1- The respective parties, the lessor and lessee, whose deed the lease is, ...... the concurrence of the will of the contracting parties took place or not. ...
www.supremelaw.org/ref/dict/bldl1.htm -


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Note added at 20 mins (2007-08-21 07:21:41 GMT)
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concours des volontés: le moment où deux parties arrivent à un accord sur un objet précis

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Note added at 28 mins (2007-08-21 07:30:35 GMT)
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Also: MUTUAL CONSENT


The consent of the parties, which is of the essence of the contract of. sale, consists in a concurrence of the will of the seller, to sell . . . , and of ...
www.law.indiana.edu/ilj/volumes/v79/no3/ricks.pdf

This can certainly be simplified in English - and, in my opinion, improved thereby - but if for any reason you feel the notion of "volonté" betrays something - such as interminable wrangling prior to this agreement - and that this is important and must be conveyed in the translation (maybe some francophones will comment on the possible connotations of the French), then you might want to consider something like:

The two parties came together/came to be of one mind regarding the terms ...

If you want to retain the legal flavour

an agreement is reached when the wills of the contracting parties coincide -this is the static case , or converge -in the dynamic approach.This consent mainly concerns the details contained in the contractual clauses,besides the simple will of reaching an agreement.
another alternative could be :
the parties consent upon the contractual clauses

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Note added at 2 hrs (2007-08-21 10:01:03 GMT)
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or the parties consent upon the clauses of this present contract