measure_distance

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It specifies the unit and the single-atom requirement, which are useful constraints, but it does not mention potential side effects (likely none), prerequisites (e.g., loaded structure), or error conditions if selections are invalid.

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 a single, front-loaded sentence that directly states the action, object, unit, and required inputs. It contains no redundant information and is appropriately concise.

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 simple measurement tool with a fully described input schema and an output schema, the description provides the core semantics: what is measured, the unit, and the single-atom selection requirement. It is sufficiently complete, though it could benefit from explicit usage boundaries or prerequisities, which are minor for this tool.

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 100%, with each parameter described as 'Single-atom selection.' The overall description adds the unit and that the two selections together define the distance, but it does not elaborate on selection syntax or format beyond what the schema already provides. This meets the baseline for schema-heavy parameters.

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 uses a specific verb 'Measure' with resource 'distance' and includes unit 'Angstroms' and the constraint 'between two single-atom selections'. This clearly distinguishes it from sibling tools like measure_angle and measure_dihedral, which measure different geometric quantities.

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 clearly indicates the tool is for distance measurement between two atom selections, providing sufficient context for when to use it. However, it does not explicitly mention alternatives or exclusions, though the name and sibling context make the distinction obvious.

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