create_side_by_side

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds one meaningful behavior ('Labels are added above each image if label_height > 0') and implies creating a new composite rather than mutating the inputs. Still, it does not state whether the source images are left untouched, where the composite gets stored, or any side effects on session state.

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?

Three sentences, each earning its place: the primary operation, the use cases, and the one non-obvious behavioral nuance. The core action is front-loaded and no filler or repetition of schema fields exists.

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 moderate-complexity tool (7 params, 2 required, output schema present), the description covers the purpose, realistic scenarios, and the key labeling behavior. Return value handling is presumably covered by the output schema. The only meaningful gap is the missing contrast with `compare_images`, which affects routing rather than invocation correctness.

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 100%, so the baseline is 3. Every parameter already has a meaningful description ('ID of the first (left) image,' 'Background color for gap and labels'). The description adds marginal value by explaining that label_1/label_2 render above each image and that label_height toggles them, but this mostly restates schema hints like '0 to disable labels.'

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 action and resource: 'Create a side-by-side comparison image from two images.' It clearly describes the output artifact and inputs. However, it does not distinguish itself from the sibling tool `compare_images`, which plausibly overlaps in intent, so an agent must infer the difference between a composite side-by-side image and an actual comparison operation.

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 clear usage context: 'Useful for visual comparisons, before/after documentation, or A/B testing screenshots.' This tells an agent when to reach for it. However, it offers no explicit exclusions, such as 'for pixel-diff or similarity analysis use compare_images instead,' leaving the boundary with that sibling unstated.

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