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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds valuable behavioral details: the exact sources searched, the shape of each result (URLs, size, license info, flags, attribution), and the result limit. No contradiction with annotations.

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?

Four tight sentences, each carrying useful information. The main purpose is front-loaded, followed by result contents, use case, and limit. No filler or repetition of schema details.

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 read-only search tool with strong annotations, the description is complete: it names sources, describes return fields, states the reuse-oriented use case, and caps results. No output schema exists, but the result structure is described well enough for an agent to invoke and interpret the 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 coverage is 50%, so the description needs to compensate. It adds meaning for 'query' ('by keyword') and 'max_results' ('Up to 12 results'), but it does not explain the 'orientation' parameter and only indirectly hints at license filtering. This is partial compensation, not full.

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?

States a specific verb ('Search'), a resource ('openly licensed images'), and a defined scope across named sources (Openverse, NASA, The Met, etc.). The title and description together clearly convey the tool's function and distinguish it from general image search.

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?

Provides an explicit use case: 'Use when you need an image you are allowed to reuse.' There are no sibling tools to contrast with, so no alternatives are needed, but it does not state when not to use the tool (e.g., for non-reusable images).

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