There are very few descriptions of the of the siege works at Tellicherry during the epic defence against the forces of Hyder Ali.
The following account by William Franklin is particularly interesting, having been written shortly after the garrison was relieved.
William Franklin was a Lieutenant in the Company’s Bengal Establishment who visited Tellicherry arriving on board the ship Yarmouth.
"we came to anchor in Tellicherry roads; 16th[April 1786], having received a very polite invitation from my friend and school-fellow Mr. Ince, I went on shore, and spent several very pleasant days with him.
Among other places I saw in and about Tellicherry, I had a view of the fortifications, or rather of the regular lines drawn round Tellicherry, for the defence of the place against the Nabob Hyder Ali, during the late war. These lines are exceedingly strong; they take in a space of about three miles and a half in circumference, and are well defended by batteries and redoubts; a river runs parallel to the western angle, which breaking off from thence runs among the hills: here the English troops sustained a severe siege for several years, against the army of Hyder, under the command of Sadik Khan ; however, on the arrival of Major Abingdon with a reinforcement from the Bombay settlement, the garrison made a most spirited and successful sally, in which having defeated the enemy and killed great numbers of them, they at length compelled them to raise the siege ; obtaining, at the same time, a considerable booty of horses, tents, and elephants. The general of the enemy was dangerously wounded and taken prisoner, and died a few days after, of that and a broken heart, at Tellicherry. I am informed that if he had lived and returned to the presence, he would have been cashiered, as the Nabob Hyder had set his heart on the reduction of the place. He lies buried close to the fort of Tellicherry; a tomb has been erected to him, in which lamps are continually burning, which many Mussulmen visit out of respect to the memory of the deceased. The lines in some parts appear rather out of order, as they have not been thoroughly repaired since the siege of the place, and I am inclined to think a great number of troops would be requisite for their defence against a resolute enemy, owing to their great extent; they are now repairing throughout, as the government entertain an idea of the importance of the place, which is certainly considerable, in case of a war with Hyder, as by his being in possession of it be might greatly injure the other settlements of the English on the Malabar Coast.
The garrison of Tellicherry consists generally, in time of peace, of one battalion of sepoys, a company of artillery, and sometimes a company of European infantry; they are also able to raise about three thousand native militia. The view of the country round Tellicherry is very pleasant, consisting of irregular hills and vallies. The boundaries of the English are terminated by the opposite side of the river, and at a very little distance is a strong fortress of the Nabob Hyder; if the lines were once to be forced,. the place would soon fall, the fort of Tellicherry itself having no kind of defence. Tellicherry is esteemed by all who reside there, to be one of the healthiest places in India, Europeans seldom dying there; it is also much resorted to by convalescents: the sea produces plenty of very fine oysters, and provisions of all kinds are to be had in abundance.
I observed, in the Company's garden, the pepper vine, which grows in a curious manner, and something similar to the grape; the pepper on it, when fit to gather, appears in small bunches ; it is in size something larger than the head of a small pea ; the pepper, however, for the Company's ships' cargoes, is brought from some distance in the country. Tellicherry also produces the coffee tree. 
 A general collection of voyages and travel, digested by J. Pinkerton.Pages 233 & 234.