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

With no annotations provided, the description must fully disclose behavior. It only states the return of B-factors, omitting details such as output format (e.g., list, array, map), error handling, or whether it modifies state. Minimal behavioral insight is provided beyond the raw function.

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 to the point, with three separate lines for purpose, aliases, and example. No redundant information. However, the structure could be improved by adding a brief explanation of the 'spec' parameter, but overall it efficiently conveys the core information.

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 presence of an output schema and a single parameter, the description covers the basic purpose but lacks details on parameter syntax and output structure. For a simple query tool, it is adequate but not thorough. Additional context about selection format would improve completeness.

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 single parameter 'spec' has no description in the input schema (0% coverage). The description lists an example ('/A:501') and mentions 'selected atoms', but does not explain the syntax or semantics of the selection string. Users must infer the format from the example, which is insufficient for reliable use.

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 tool returns B-factors for selected atoms, using a specific verb ('Return') and resource ('B-factors'). The aliases help clarify terminology, and the example further solidifies the purpose. Among sibling tools, none directly compete for B-factor retrieval, so differentiation is inherent.

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?

No guidance on when to use this tool versus alternatives is provided. There is no mention of prerequisites, limitations, or situations where another tool might be more appropriate. The description assumes the user already knows they need B-factors, offering no context for selection or comparison with siblings.

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