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

The description goes beyond the readOnlyHint annotation by detailing pagination behavior and return format ('Returns {items: [...], next_cursor: str | null}'). This provides critical behavioral context that helps an agent understand how to iterate results, with no contradictions to 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?

The description is concise at approximately 6 lines, front-loaded with the main purpose, and uses well-structured bullet points for filters and pagination. Every sentence adds value without redundancy, making it easy for an agent to parse.

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 the description's coverage of filters, pagination, and return format, the description is fully complete for this tool. It addresses all necessary aspects without relying solely on structured fields.

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 100%, so the baseline is 3. The description adds value by elaborating on the source filter (e.g., explicitly mentioning 'generated' images) and explaining pagination cursor usage, which is not fully captured in the schema descriptions. This enhancement justifies a 4.

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 'List hosted images owned by the caller, with optional filters,' specifying a verb (list) and resource (hosted images). This distinguishes it from sibling tools like get_image (single image) and delete_image, making the purpose immediately clear.

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 implies use for retrieving multiple images with optional filters but does not explicitly contrast with alternatives like get_image for individual images or upload_image. The usage context is clear but lacks explicit when-not or sibling differentiation.

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