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STRING Database MCP Server

STRING: Protein–protein interaction (PPI) enrichment

string_ppi_enrichment

This tool tests if your network is enriched in protein-protein interactions compared to the background proteome-wide distribution (i.e., if your proteins are more functionally connected than expected by chance).

  • The enrichment is assessed using the actual observed edges versus expected edges in a random network of the same size.

  • The p-value reflects the likelihood that your observed number of interactions would occur by chance.

  • Report the p-value as a human-readable value (e.g. 2.3e-5 or 0.023).

When calling related tools use the same input parameters unless otherwise specified.

Output fields:

  • number_of_nodes: Number of proteins in your network

  • number_of_edges: Number of observed edges/interactions

  • average_node_degree: Mean degree (average number of interactions per node)

  • local_clustering_coefficient: Average clustering coefficient in the network

  • expected_number_of_edges: Expected number of edges in a random network of the same size

  • p_value: p-value for network enrichment (smaller = more enriched)

Example identifiers: "SMO%0dTP53"

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
speciesNo
identifiersYesRequired. One or more protein identifiers, separated by %0d. Example: SMO%0dTP53
required_scoreNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

TDQS

B3.4/5.0
Behavior3/5

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

With no annotations, the description carries the full transparency burden. It discloses the statistical methodology (observed vs expected edges) and provides output field interpretations (e.g., 'p_value: smaller = more enriched'). However, it does not mention potential side effects (though likely none), prerequisites like species handling, or behavior under invalid input, leaving gaps.

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

Conciseness3/5

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

The description is well-structured with bullets and an output field list, but it includes extraneous elements like 'Report the p-value as a human-readable value' and 'When calling related tools...' which are not core tool-defining content. It could be tightened without losing key information.

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

Completeness3/5

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

An output schema exists, so listing return fields is redundant but adds interpretive value. The description does not address when to provide required_score or how species defaults behave, and it lacks guidance on input prerequisites. It is adequate for basic selection but not fully complete for invocation without schema inspection.

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

Parameters2/5

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

Schema description coverage is low (33%), so the description must compensate. It provides an example identifier format ('SMO%0dTP53') but does not clarify the semantics of the optional species or required_score parameters beyond what the schema already says. The phrase 'use the same input parameters' adds little specific value.

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 starts with a specific verb ('tests if your network is enriched') and clearly identifies the resource (protein-protein interactions) and the comparison (background proteome-wide distribution). This distinguishes it from sibling tools like string_enrichment, which likely focus on functional term enrichment.

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

Usage Guidelines3/5

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

The description implies usage when one wants to assess whether a protein set is more functionally connected than random, but it does not explicitly state when to choose this tool over alternatives such as string_enrichment or string_network_clustering. The only related-tool note ('When calling related tools use the same input parameters') is about parameter reuse, not tool selection.

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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TDQS

A3.6/5.0
Disambiguation2/5

Several tool pairs have overlapping purposes: string_network_link and string_visual_network both return network URLs with nearly identical behavior, and string_all_interaction_partners vs string_interactions_query_set both query interactions, differing subtly in scope. The enrichment/annotation tools also share boundaries, making it difficult for agents to disambiguate without reading detailed descriptions.

Naming Consistency3/5

All tools share the 'string_' prefix, but the pattern is inconsistent: some are verb-first (create_file, resolve_proteins), some are noun-first (interactions_query_set, network_link), and some are bare nouns (enrichment, homology). This mixed convention reduces predictability.

Tool Count4/5

At 17 tools, the server is slightly above the ideal range, but it covers a broad domain: interactions, networks, enrichment, annotation, homology, species resolution, and sequence search. The count is justified by the complexity of the STRING database.

Completeness4/5

The tool set covers core STRING workflows: querying interactions, constructing networks, computing enrichment, retrieving annotations, identifying homologs, mapping IDs, and exporting data. Minor gaps exist (e.g., direct edge-list tables and intricate interaction score details), but the overall surface is robust.