> ## Documentation Index > Fetch the complete documentation index at: https://proto.evodesign.org/docs/llms.txt > Use this file to discover all available pages before exploring further. # Metal3D Probability > Reward protein sequences whose prepared structures contain high-probability Metal3D metal-ion sites.

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evo-design/proto-language/proto\_language/constraint/protein\_structure/metal3d\_probability\_constraint.py

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Score proposals by Metal3D metal-site probability; lower is better. ## API Reference

ConfigMetal3DProbabilityConfig Source

Configuration for the Metal3D probability constraint. Single Metal3D probability floor for detection, annotation, and scoring; overrides tool threshold. Metal3D tool configuration; its probability\_threshold is overridden by min\_probability. How to obtain proposal-specific structures before Metal3D scoring. Optional candidate residues to pass to Metal3D.

## Usage ```python python icon="python" theme={null} from proto_language.core import Constraint from proto_language.constraint import metal3d_probability_constraint, Metal3DProbabilityConfig constraint = Constraint( inputs=[segment], function=metal3d_probability_constraint, function_config=Metal3DProbabilityConfig( # Configure parameters here ), ) scores = constraint.evaluate() ``` ## Metadata | Property | Value | | --------------- | -------------------------------- | | Key | `metal3d-probability` | | Function | `metal3d_probability_constraint` | | Category | `protein_structure` | | Mode | `discrete` | | Uses GPU | `True` | | Supported Types | `protein` |