Edit image

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

The description adds behavior beyond the annotations: "saves the result as a NEW file (never overwrites sources)" and "returns the absolute saved path(s)." These safety and outcome details are valuable context that annotations (readOnlyHint=false, destructiveHint=false) do not provide. No contradiction with 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 three sentences: first states the core purpose and allowed operations, second explains input/output behavior, third states the return value. Every sentence earns its place, with no redundancy or filler. It is front-loaded with the most important information.

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 12-parameter tool with no output schema, the description covers the essential context: what it does, source handling, non-destructive output, and return value. The rich parameter details are already in the schema, so the description is complete without being verbose. Slight gap: it does not mention provider-specific variations, but those are documented in the schema.

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 fully documents all 12 parameters. The description itself does not elaborate on any parameter semantics, but the baseline 3 is appropriate since the structured data carries the burden and does it well.

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 opens with a specific verb+resource: "Edit or combine existing image file(s) using a text instruction," and lists concrete operations (modify, restyle, add/remove content, merge references). This clearly distinguishes it from the sibling generate_image tool, which creates new images rather than editing existing ones.

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 makes it clear the tool is for existing image files ("Reads the source image(s) from disk"), implying the alternative generate_image for new images. However, it does not explicitly state when not to use this tool or name the sibling alternatives, leaving a small gap in explicit guidance.

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