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

Annotations already cover the safe-read profile (readOnlyHint, idempotentHint, non-destructive, closed-world), so the description's job is to add scope. It does: it discloses that results span both user uploads and server-generated files and that sizes are included, which is genuinely useful return-content information not present in the schema or annotations. It stays silent on ordering, pagination, or result limits, which is the only remaining gap.

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?

A single sentence with the scope ('for your token') and the payload ('with their sizes') front-loaded. Nothing is redundant or padded.

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 zero-parameter, annotation-covered listing tool with no output schema, the description covers what is listed and what metadata comes back. Adding return ordering or any result-limit behavior would make it fully complete, but nothing an agent needs in order to call it correctly is missing.

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 tool takes zero parameters, so the baseline is 4. The description correctly implies no filtering inputs are needed, and there is no parameter semantics left to explain.

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 and resource ('List the images stored for your token') and scopes the contents to both uploaded and server-written images. It does not, however, distinguish itself from siblings such as image_info or image_thumbnails, so an agent must infer that this is the enumeration tool rather than a per-image lookup.

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 phrase 'List the images stored for your token' implies the discovery/enumeration use case, but there is no explicit when-to-use statement, no mention of when not to use it, and no reference to an alternative like image_info for single-image details. Usage is left to inference.

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