rcsb_get_nonpolymer_entity_groups

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds valuable behavioral context: the default fields returned, that unknown group IDs are returned under 'not_found', and that the fields argument is a GraphQL selector that replaces the default. This goes beyond what annotations provide.

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

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

The description is tightly structured with a purpose line, a default-fields line, and a clean Args section. Every sentence adds information—no fluff, no repetition of schema properties—and the format is easy to scan.

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

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

Given the tool has only two parameters and an output schema, the description covers the core purpose, default output, parameter semantics, and how to extend the query. It leaves nothing essential unexplained; the output schema handles return value details, so the description is complete.

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

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

Schema description coverage is 0%, so the description must fully compensate, and it does. It explains group_ids with an example and the 'not_found' behavior, and fields with an example and a pointer to rcsb_describe_data_object for discovering valid paths. Both parameters are clearly documented beyond their schema definitions.

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

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

The description states a specific verb ('Fetch') and resource ('non-polymer entity groups') with a clarifying parenthetical ('clusters of related ligands'). It distinguishes from sibling tools like rcsb_get_polymer_entity_groups and rcsb_get_nonpolymer_entities by explicitly naming the entity-group scope.

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

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

The description implies usage when one needs nonpolymer entity group data by ID, but it does not explicitly state when to use this tool over alternatives or mention exclusion criteria. There is no 'when to use' or 'when not to use' guidance beyond the resource name, so it remains at the implied-usage level.

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