The narrators tone in "London" acts as a door into his/her character. Through the tone we can decipher the observer's view of his setting, London. This is what tells us about him/her. The narrators tone is generally playful, making witty remarks throughout the poem. The narrator, thusly, seems like a witty and charismatic figure. However, if you take a closer look you can see an underlying somber tone. The narrator feels "chartered", rigidly clamped as opposed to free in a bustling metropolis. He feels that London is cluttered to the narrator. He finds it to be dirty and revolting, calling the Thames river "chartered". He finds the people frail and depressing, utterly disheveled. Much like with the city he despises the people. He feels as though all of the city is shackled in "mind-forged manacles". the phrase "hapless soldier's sigh" offers yet another dimension to the narrator's discontent. He feels oppressed and constricted, as though the air in London chokes him. He sees everything, even the cries of vendors, as cries of disdain begging for help.
Personally, I find the narrator to seem paranoid. He sees everything as negative. He has no balance or counter to his negative beliefs. He acts like his life has no upside and that the city is taking everything from him. His tone, in my opinion, makes him seem paranoid, obsessive, and desperate for a belief to cling to.