Overview

Experimental (PDB) and predicted (AlphaFold) protein structures behind one surface. Search, fetch, align, and annotate structures and their ligands across RCSB, AlphaFold DB, 3D-Beacons, UniProt, InterPro, and Foldseek. No API key required.

Tools

Resources

Both resources are also reachable through protein_get_structure, for clients that don't surface resources.

Capability reference

protein_search_structures _tool

• At least one of query, sequence (an mmseqs2 search; min_identity / max_evalue apply only with it), organism, method, or max_resolution; content_type is experimental, predicted, or all (default); up to 100 hits per page (default 25) via limit / start
• A sequence needs at least 10 residues; whitespace is stripped and case normalized, and an invalid one fails as invalid_sequence. Each hit names its source and an entry id you can pass to other tools
• Optional facets (method, organism, polymer_type, resolution, release_year, molecular_weight) add a breakdown capped at PROTEIN_FACET_BUCKET_CAP buckets per dimension

protein_get_structure _tool

• source: experimental (default) takes PDB entry IDs and the AF_* / MA_* computed-model IDs search returns (these come back as source: predicted); predicted takes UniProt accessions for AlphaFold models with pLDDT/PAE; best_available takes UniProt accessions and returns the highest-resolution experimental structure, else the best prediction. Up to PROTEIN_MAX_BATCH_IDS IDs per call (default 25)
• Unresolved IDs land in failed[], and requested / processed show IDs dropped past the cap; the call fails as all_failed when nothing resolves and mixed_id_types when the IDs don't fit source. Records include coordinateUrls for the files that exist
• include_coords inlines coordinate text within a size budget; an over-budget batch returns an overflow outline to re-call with sections: [ids]

protein_find_similar _tool

• by: sequence runs a synchronous RCSB mmseqs2 search from sequence, pdb_id, or uniprot, filtered by max_evalue / min_identity; by: structure runs an async Foldseek search from pdb_id or uniprot against pdb100 + afdb50 unless databases says otherwise. A field only the other mode reads fails as mode_mismatched_field; up to 100 hits per page (default 25)
• Sequences follow the same rules as protein_search_structures, and a direct sequence wins over identifiers. Hits name their source (and database for structure hits), ranked by score; responses report totalCount and nextStart
• A structure job still running at the poll budget returns status: computing with a ticketId; re-call with ticket_id to resume it. A multichain structure is searched one chain at a time via query (0-based, default 0) out of queryCount

protein_track_ligands _tool

• mode is find_ligand (query: a name or formula), structures_with_ligand (comp_id), or binding_site (pdb_id, optional comp_id); a missing mode input fails as missing_param. limit is 1–100 (default 25), and start pages the last two modes
• find_ligand returns component IDs with formula, weight, SMILES, and InChIKey, ranked by depositionCount, with totalCount and candidatesConsidered showing when the candidate pool was cut short; structures_with_ligand lists entries highest resolution first
• binding_site returns pocket residues with contact distances, numbered in both label (asymId, seqId) and author (authAsymId, authSeqId) namespaces; it works on experimental structures only

protein_compare_structures _tool

• 2 structures up to PROTEIN_MAX_COMPARE_STRUCTURES (default 10, max 25), each a pdb_id with an optional label-namespace chain; method is tm-align (default), fatcat-rigid, or fatcat-flexible; reference is first (default) or all_pairs; timeout_s (5–120) sets the per-pair poll budget
• Each pair row has a status (complete, computing, failed), tmScore, rmsd, alignedResidues, modeledResidues, and coverage; TM-score is normalized by a's length, so reversing a pair changes it. similarityScore and sequenceSimilarity appear when the upstream supplies them
• A computing pair returns its job uuid; re-call with { a, b, uuid } in resume[] to poll it instead of resubmitting. A mismatched method or pair fails as resume_method_mismatch or resume_job_mismatch

protein_analyze_collection _tool

• group_by takes one of method, organism, polymer_type, resolution, release_year, molecular_weight, or two distinct ones for a cross-tab; scope with query, organism, method, max_resolution, and content_type (default experimental). interval sets a numeric bin width for resolution / molecular_weight or "year" for release_year
• Returns total and bucketsReturned; buckets carry label and count (numeric bins add rangeFrom / rangeTo), and every dimension reports missingValueCount
• bucket_limit (1–500, default PROTEIN_FACET_BUCKET_CAP) caps each dimension separately; truncated and notice say where results were cut

protein_get_annotations _tool

• A uniprot accession, or a pdb_id resolved through its UniProt cross-reference (author chain picks one accession); include is features, domains, variants, or all (default); limit pages each class separately (1–200, default 50), with independent zero-based features_offset, variants_offset, and domains_offset (default 0)
• Returns UniProt features and natural variants plus InterPro domains with GO terms; a PDB entry mapping to several accessions uses the lowest author chain and lists the rest in ambiguity
• Each requested class carries featuresTotal, variantsTotal, or domainsTotal; a page with more records sets truncated and names the next offset in notice
• Failures are typed as missing_identifier, invalid_accession, no_uniprot_mapping, or chain_not_found

pdb://{entry_id} _resource

• entry_id is a PDB entry ID (e.g. 4HHB); returns application/json with title, methods, resolution, organisms, ligands, and polymerEntities carrying both authAsymIds and labelAsymIds
• Same data as protein_get_structure with source: experimental

af://{uniprot} _resource

• uniprot is a UniProt accession or an AlphaFold DB entry ID (e.g. AF-P69905-F1); returns application/json with meanPlddt, confidenceBuckets, cifUrl / pdbUrl / bcifUrl, and modelVersion
• Same data as protein_get_structure with source: predicted

Features

Built on @cyanheads/mcp-ts-core: stdio and Streamable HTTP transports, pluggable auth (none / jwt / oauth), swappable storage (in-memory, filesystem, Supabase, Cloudflare KV/R2/D1), structured logging with optional OpenTelemetry tracing.

PDB / AlphaFold-specific:

• Search, fetch, and comparison treat experimental (PDB) and predicted (AlphaFold DB, ModelArchive, 3D-Beacons providers) structures the same way
• Keyless across RCSB, AlphaFold DB, 3D-Beacons, UniProt, InterPro, and Foldseek
• Collection analytics run on RCSB's facet engine and return bucket counts, not matching entries
• Foldseek and alignment jobs poll for up to PROTEIN_ASYNC_POLL_TIMEOUT_MS (default 30 s), then hand back a resume handle (ticketId, per-pair uuid) instead of blocking
• Chain namespaces stay separate: authAsymIds feed protein_get_annotations chain, labelAsymIds feed protein_compare_structures chain

Agent-friendly output:

• Provenance: every hit names its source (experimental / predicted) and the engine or database behind it, and protein_get_structure and protein_get_annotations carry an attribution block (see Upstream data licensing)
• Graceful partial failure: failed[] rows and per-pair status keep one bad ID or pair from failing the request
• Paging and advisories: paged tools return totalCount and nextStart, a start past the end is flagged in notice separately from zero matches, and every advisory joins into that one notice

Getting started

Public Hosted Instance

A public instance is available at https://protein.caseyjhand.com/mcp, no installation required. Point any MCP client at it via Streamable HTTP:

{
  "mcpServers": {
    "protein-mcp-server": {
      "type": "streamable-http",
      "url": "https://protein.caseyjhand.com/mcp"
    }
  }
}

Self-Hosted / Local

Add the following to your MCP client configuration file. No API key is needed.

{
  "mcpServers": {
    "protein-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["@cyanheads/protein-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with npx (no Bun required):

{
  "mcpServers": {
    "protein-mcp-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@cyanheads/protein-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "protein-mcp-server": {
      "type": "stdio",
      "command": "docker",
      "args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/protein-mcp-server:latest"]
    }
  }
}

For Streamable HTTP, set the transport and start the server:

MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp

Prerequisites

• Bun v1.4.0 or higher (or Node.js v24+).
• No accounts or API keys: every upstream is public.

Installation

1. Clone the repository:

git clone https://github.com/cyanheads/protein-mcp-server.git

2. Navigate into the directory:

cd protein-mcp-server

3. Install dependencies:

bun install

4. Configure environment (optional):

cp .env.example .env
# every variable has a working default

Configuration

Every variable is optional.

Each upstream's base URL can also be pointed at a mirror: RCSB_SEARCH_BASE_URL, RCSB_DATA_BASE_URL, RCSB_FILES_BASE_URL, RCSB_MODELS_BASE_URL, RCSB_ALIGNMENT_BASE_URL, BEACONS_BASE_URL, ALPHAFOLD_BASE_URL, MODELARCHIVE_BASE_URL, FOLDSEEK_BASE_URL, UNIPROT_BASE_URL, INTERPRO_BASE_URL. See .env.example for their defaults and the full list of optional overrides.

Running the server

Local development

• Build and run:

  shCopy

  # One-time build
  bun run rebuild
  
  # Run the built server
  bun run start:stdio
  # or
  bun run start:http
  

• Run checks and tests:

  shCopy

  bun run devcheck   # Lint, format, typecheck, security
  bun run test       # Vitest test suite
  bun run lint:mcp   # Validate MCP definitions against spec
  

Docker

docker build -t protein-mcp-server .
docker run --rm -p 3010:3010 protein-mcp-server

The Dockerfile defaults to HTTP transport, stateless session mode, and logs to /var/log/protein-mcp-server. OpenTelemetry peer dependencies are installed by default; build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

Development guide

See CLAUDE.md/AGENTS.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic
• Use ctx.log for request-scoped logging, ctx.state for tenant-scoped storage
• Export new definitions from the barrels in src/mcp-server/*/definitions/index.ts and register them in the createApp() arrays in src/index.ts
• Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

Upstream data licensing

Structure and annotation data comes from public databases, each under its own license. protein_get_structure and protein_get_annotations return an attribution block with the license, citation, and homepage of every source that contributed to that response. CC BY and CC BY-SA sources require attribution on redistribution; CC0 sources ask only for citation.

best_available models arrive through 3D-Beacons, so the block credits the provider that actually supplied the model; a provider with no curated entry gets a See provider terms fallback instead of a guessed license. InterPro and GO are credited separately, each only when it contributes. This table covers upstream data; the server's own code is licensed separately (see License).

Contributing

Issues are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

License

Apache-2.0 — see LICENSE for details.