---
title: Paragraph inputs and parameters
description: Up to 20 sequences and the probability threshold that decides which residues are paratope — plus why only imgt works, since a chothia request is rejected.
tags:
  - paragraph
  - inputs
---

You provide antibody variable-region sequences and set the chain type and a probability threshold. The threshold is the knob that decides which residues get called paratope: lower it to catch marginal contacts, raise it for a high-confidence core. The chain type tells Paragraph which chain's residues to report.

## Sequences

- `sequences` (string[]) —
Antibody variable-region amino acid sequences. One to 20 per job.

- `sequence_names` (string[]) —
Optional names for each sequence.

## Chain type and scheme

- `chain_type` (string) —
Chain type: `H` for heavy, `L` for light.

- `scheme` (string) —
Numbering scheme for position annotation. Only `imgt` actually works — Paragraph's region boundaries are IMGT-only, and a `chothia` request is rejected with an error rather than silently mislabeled. For Chothia numbering, use [ANARCI](/docs/anarci) instead.

## Threshold

- `threshold` (float) —
Probability at or above which a residue is called part of the paratope (0.0–1.0).

## Read next