rcsb_get_interfaces

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

Annotations already declare read-only and idempotent behavior, so the description doesn't need to restate that. It adds useful quirks: unknown IDs are returned under 'not_found', and `fields` replaces the default selection. This provides behavioral insight 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.

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

The description is well-structured with a one-line purpose, a default-fields note, and an Args list. Every sentence adds value — no padding or redundancy.

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?

For a 2-parameter tool with an output schema, the description covers purpose, argument semantics, defaults, unknown-ID handling, and field customization. It is self-contained and gives the agent everything needed to invoke correctly without requiring the schema alone.

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 fully compensates. `interface_ids` is explained with format and error behavior; `fields` gets a clear explanation, an example GraphQL path, and a discovery method. This is far beyond what the bare schema offers.

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 starts with 'Fetch assembly interfaces' — a specific verb and resource — and gives the exact format (e.g., ["1BMV-1.1"]). This clearly distinguishes it from sibling `get_*` and search tools.

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 gives clear context for when to use this tool (fetching interfaces by IDs) and explains the `fields` parameter with a pointer to `rcsb_describe_data_object` for discovering paths. It does not explicitly contrast with sibling tools, but the usage context is informative and actionable.

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