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io.github.rcsb/rcsb-mcp

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rcsb_search_by_seqmotif

Read-onlyIdempotent

Find RCSB PDB polymer entities (proteins, DNA, RNA) that contain a specific sequence motif using PROSITE, regex, or simple wildcard patterns, and retrieve matching structure IDs with scores.

Instructions

Find polymers containing a short sequence motif (PROSITE / regex / simple).

Args: pattern: The motif, e.g. "C-x(2,4)-C-x(3)-[LIVMFYWC]-x(8)-H-x(3,5)-H" (prosite), "C..H[LIVF]" (regex), or "NXS" (simple wildcards). pattern_type: "prosite" (default), "regex", or "simple". sequence_type: "protein" (default), "dna", or "rna". return_type: What to return (default "polymer_entity"); see the "Return types and fetching details" note in the server instructions. limit: Max hits (1-100). offset: Number of hits to skip, for paging; pass the response's next_offset back with the same query to fetch the next page. all_hits: Return the COMPLETE result set in one call (for an explicit "ALL ..." request); ignores limit, can't be combined with offset, and is refused above 10000 hits. Ignored when facets is set. attributes: Optional structured filters AND/OR-combined with this match — a list of AttributeFilter {attribute, operator, value, negation?, case_sensitive?} (e.g. restrict to an organism or resolution). See rcsb_search_by_attribute / rcsb_list_pdb_search_attributes for paths and operators. logical_operator: Combine this match and the attribute conditions with "and" (default) or "or". facets: Optional aggregation specs to return a breakdown / distribution instead of hits (see the faceting note in the server instructions for the spec). group_by, group_by_ranking: Collapse redundant polymer_entity hits into clusters, one representative each (needs return_type="polymer_entity") — see the grouping note in the server instructions. sort_by: Attribute path to order the hits by, replacing the default score ordering (each hit's score is still returned); omit to keep it. Only SORTABLE attributes work: those listing exact_match (strings) or equals (numbers/dates) in rcsb_list_pdb_search_attributes; full-text-only attributes (e.g. struct.title) and return_type="mol_definition" are rejected. sort_direction: "asc" (default) or "desc"; applies only when sort_by is set.

Returns: {total_count, returned, offset, has_more, next_offset, hits:[{id, score}], editor}; with facets, instead returns {total_count, facets, editor}.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
limitNo
facetsNo
offsetNo
patternYes
sort_byNo
all_hitsNo
group_byNo
attributesNo
return_typeNopolymer_entity
pattern_typeNoprosite
sequence_typeNoprotein
sort_directionNoasc
group_by_rankingNo
logical_operatorNoand

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the readOnly/openWorld/idempotent annotations, the description richly discloses behavior: return format, pagination via next_offset, all_hits constraints (ignores limit, cannot combine with offset, refused above 10000, ignored with facets), sort_by restrictions (only sortable attributes, rejects full-text and mol_definition), and grouping behavior. This goes well beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is long but tightly structured with an Args list and a Returns section. Every sentence provides essential information about a parameter or return behavior; there is no fluff. The purpose is front-loaded, and the labeled sections make it easy to scan.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with 14 parameters, an output schema, and complex behaviors (pagination, faceting, grouping, sorting, attribute filters), the description covers all necessary aspects: pattern syntax, pattern types, sequence types, return types, error conditions (e.g., mol_definition rejection), and exact return structure. It is fully self-contained modulo server-instruction references.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% for the main properties, but the description compensates fully by explaining every parameter with examples, defaults, valid values, and cross-parameter interactions (e.g., all_hits vs offset, group_by requiring return_type='polymer_entity'). This is exemplary compensation for sparse schema descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb+resource: 'Find polymers containing a short sequence motif (PROSITE / regex / simple).' This clearly distinguishes it from sibling tools like rcsb_search_by_sequence (full sequence) and rcsb_search_strucmotif (structure motif).

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear context for when to use the tool (searching by sequence motif with specific pattern types and sequence types), but it does not explicitly name alternatives or state when not to use it. It references server instructions for related details, but lacks direct exclusionary guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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