> ## 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. # Structure pLDDT Score > Evaluate structure quality using predicted LDDT score
Structure pLDDT Score
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Structure Prediction ยท 7 tools
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evo-design/proto-language/proto\_language/constraint/protein\_structure/structure\_confidence\_constraint.py
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Evaluate structure quality using predicted LDDT (pLDDT) score. pLDDT (predicted Local Distance Difference Test) measures per-residue confidence in the predicted structure. Values range from 0.0 to 100.0 (sometimes, these are normalized from 0.0 to 1.0) where higher values indicate more reliable predictions. This constraint returns 1.0 - **normalized** pLDDT, so lower scores indicate better predicted structure quality. Note that for Boltz2, this is based on the `"complex_plddt"` score returned natively by the package. **Supported tools**: ESMFold, ESMFold2, AlphaFold3, Boltz2, Chai1, Protenix, AlphaFold2, AlphaFold2 binder ## API Reference
ConfigStructureBasedConstraintConfig Source
Base configuration for constraints using structure prediction tools. This base class standardizes how structure prediction tools and their configurations are specified across all structure-based constraints. Each tool has its own dedicated config field. Subclasses can optionally restrict which tools are supported by overriding the structure\_tool field with a narrower Literal type. Predictor: esmfold/esmfold2/alphafold3/boltz2/chai1/protenix/alphafold2/alphafold2\_binder. Options: `esmfold`, `esmfold2`, `alphafold3`, `boltz2`, `chai1`, `protenix`, `alphafold2`, `alphafold2_binder` Configuration for ESMFold structure prediction. Configuration for ESMFold2 structure prediction. Configuration for AlphaFold3 structure prediction. Configuration for Boltz2 structure prediction. Configuration for Chai1 structure prediction. Configuration for Protenix structure prediction. Configuration for the general AlphaFold2 multimer structure predictor. Configuration for the AF2 binder-design backend.
ReturnsConstraintOutput
Per-proposal score and `avg_plddt` / `pdb_output` / `structure_tool` metadata for the predicted full input tuple; predicted Structure attaches to slot 0.
## Usage Programming a homo-trimer with ESMFold: ```python python icon="python" theme={null} >>> from proto_language.core import Segment >>> protomer = Segment(length=10, sequence_type="protein") >>> esmfold_plddt = Constraint( ... inputs=[protomer, protomer, protomer], ... function=structure_plddt_constraint, ... function_config={"structure_tool": "esmfold"}, ... ) ``` ## Metadata | Property | Value | | --------------- | --------------------------------- | | Key | `structure-plddt` | | Function | `structure_plddt_constraint` | | Category | `protein_structure` | | Mode | `discrete` | | Uses GPU | `True` | | Supported Types | `protein`, `rna`, `dna`, `ligand` |