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

Annotations provide little safety context (readOnlyHint=false, destructiveHint=false), so the description carries the burden. It adds valuable behavioral details: no AI, exact-pixel resizing, dimensions snapping to multiples of 8, and center-crop behavior on aspect mismatch. It does not mention persistence or return format, but the core behavior is disclosed.

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 compact and front-loaded with the primary behavior, then immediately gives alternatives and key constraints. Every sentence adds useful information without repetition.

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?

The description captures the core operation, sibling differentiation, and important dimension behavior, but it is incomplete for a tool with four parameters, zero schema descriptions, and no output schema. The required creationIdentifier parameter is opaque, and the agent gets no guidance on what it identifies or whether folderReference is needed.

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 description coverage is 0%, so the description must compensate. It gives meaningful semantics for width and height ('exact pixels', 'snap to multiples of 8', 'center-crop'), but the required creationIdentifier parameter and the optional folderReference parameter are not explained. This is a meaningful gap for correct invocation.

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?

Description clearly states this resizes to exact pixels with no AI, references the images resource, and explicitly distinguishes itself from images_upscale and images_crop siblings. It is specific about what the tool does and how it differs from closely related operations.

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 direct alternatives: use images_upscale for real detail upscaling and images_crop for aspect adjustments. This explicitly tells the agent when to choose this tool versus its siblings.

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