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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds meaningful behavioral context by explaining that images return a visual preview while videos and PDFs return only a text note. This goes beyond the annotations and helps set expectations.

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 compact sentences with no filler. The core purpose is front-loaded, and the illustrative 'pink hat' example adds clarity without bloating the text.

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 single-parameter read-only tool, the description covers the main behavior, the unsupported media types, and the prerequisite. It does not specify the exact preview format (e.g., image URL vs. inline data), but the lack of an output schema makes that a minor gap.

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 schema already fully documents the single 'id' parameter with a description and provenance ('from list_media or upload_media'). The description reinforces using list_media first, which is helpful, but adds little beyond the schema's own documentation.

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 a specific verb and resource: 'See an uploaded image' and 'returns a small preview of the picture itself.' It also clarifies scope by saying images only, and distinguishes the tool from other media operations clearly.

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 gives explicit guidance: 'Images only; videos and PDFs return a text note' and 'Use list_media first to get ids.' This tells the agent when the tool is useful and what prerequisite step is needed, though it does not name an alternative tool for non-image media.

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