overlay

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

With no annotations provided, the description carries full responsibility for behavioral disclosure. It transparently states that output is written to a new file, sources remain untouched, alpha channel is respected, opacity is configurable, and it returns the output path and offset. This is comprehensive for a compositing tool.

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?

Two sentences, front-loaded with the core purpose and a key safety caveat (new file). Every clause adds value; no redundancy or filler.

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?

Even without an output schema, the description explicitly states the return value (output path and offset) and covers the essential behavior needed to invoke the tool correctly. For a straightforward image overlay with this parameter set, nothing critical 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?

Schema description coverage is 100%, so the schema already documents all parameters (base, overlay, out, x, y, opacity). The description adds contextual flavor (offset placement, alpha mix) but does not materially exceed schema details; baseline 3 is appropriate.

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 ('composite'), the resources (images), and the result (new file, sources unchanged). Clearly distinguishes from siblings like watermark and resize by detailing the overlay placement and opacity behavior.

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 explicit use cases ('logos, badges, or layering') that help an agent decide when to apply this tool. Does not explicitly exclude alternative tools (e.g., watermark), but the context is strong enough to guide selection.

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