list_available_molecules

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

With no annotations, the description carries the full burden. It indicates read-only behavior ('List') and adds the scope that it lists only built-in definitions, but it does not describe return format, pagination, or any potential limitations beyond the .def note. This is adequate but not rich behavioral disclosure.

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 two short sentences. The first sentence immediately states the core purpose; the second adds critical operational context. Every word is purposeful with no 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 simple, parameter-less listing tool without an output schema, the description covers the core behavior and a key limitation (manual .def for missing molecules). It could mention output format, but that's not necessary given the simplicity. The description provides sufficient context for selection and invocation.

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?

The tool has zero parameters, so the baseline is 4. There is nothing to explain about parameter semantics, and the schema already documents no properties. The description doesn't need to compensate.

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 'List all built-in molecule definitions with metadata,' which clearly specifies the verb (list) and resource (built-in molecule definitions). The addition of 'with metadata' provides specific scope, and it distinguishes from siblings like list_available_forcefields and get_molecule_definition.

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 second sentence, 'Molecules not listed here require manual .def file construction,' implies a use case: check if a molecule is built-in and if not, you will need to construct a .def file. While it doesn't explicitly name alternatives, it provides decision-relevant context about when this tool is needed versus manual construction.

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