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

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions the tool searches photos but doesn't cover critical aspects like rate limits, authentication requirements, pagination behavior beyond parameters, or error conditions. The return format is described, but operational context is missing.

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 and efficiently organized with clear sections for Args and Returns. Every sentence adds essential information without redundancy, making it easy to parse while maintaining completeness for the tool's functionality.

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 tool's moderate complexity (6 parameters, 1 required) and lack of annotations/output schema, the description does well by detailing parameters and return format. However, it misses some behavioral context like rate limits or authentication needs, preventing a perfect score.

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 description adds significant value beyond the input schema, which has 0% schema description coverage. It clearly explains each parameter's purpose, constraints (e.g., '1-30' for per_page), and valid values for enums like order_by, color, and orientation. This fully compensates for the schema's lack of descriptions.

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's purpose: 'Search for Unsplash photos'. It specifies the verb ('Search') and resource ('Unsplash photos'), making the function immediately understandable. However, without sibling tools to differentiate from, it cannot achieve the highest score of 5 which requires distinguishing from alternatives.

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 provides no guidance on when to use this tool versus alternatives, prerequisites, or constraints. It simply lists parameters and returns without context about appropriate use cases, making it minimally helpful for decision-making.

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