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

No annotations are provided, so the description must disclose behavioral traits. It does not mention side effects (e.g., caching, state changes), prerequisites (e.g., internet for PDB ID), or error handling for invalid sources. This is a significant gap for a tool that may have non-obvious behavior.

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 short and front-loaded, with aliases and an example in minimal space. Every sentence is useful; no fluff or repetition. The structure is effective.

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 tool with low complexity (one parameter) and an output schema, the description covers the essential purpose. However, it omits details about return values, error behavior, or performance considerations, which could be helpful for an agent. The completeness is adequate but not exhaustive.

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 coverage is 0%, and only one parameter 'source' exists. The description adds meaning by listing valid input types (PDB ID, file path, URL), but does not specify exact formats or constraints. This provides some value beyond the raw schema, but not enough to exceed baseline 3.

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 clearly states the verb 'Open' and the resource 'molecular structure', and specifies three distinct source types (PDB ID, file path, URL). It effectively distinguishes from sibling tools like close_structure and save_structure. The example reinforces the purpose.

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 lists aliases and provides an example, but does not explicitly state when to use this tool versus alternatives. However, given the sibling tools, it is clear that this is the primary tool for opening structures, so usage context is implicit. Lack of explicit when-not or prerequisites prevents a higher score.

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