generate_image

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

With no annotations, the description carries the full behavioral burden. It usefully discloses the side effect (saves the image to disk) and the return value (file path), which is the most important trait for an agent. However it omits cost/latency of the external API call, permission requirements, and what happens if 'filename' collides with an existing file.

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 verb and side effect before the trigger list. Every phrase earns its place and there is no padding or restatement of the tool name.

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?

Since there is no output schema, the description correctly compensates by stating that a file path is returned. Combined with 100% schema coverage on the four parameters, an agent has enough to invoke it correctly; only secondary details (cost, overwrite behavior) are 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 every parameter (model, prompt, filename, aspect_ratio) is already documented in the schema. The description adds no parameter-level detail beyond what the schema provides, so the 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+resource ('Generate an image') and names the underlying model (Nano Banana / Gemini). It also distinguishes itself from the sibling tools (list_models, set_model), which are model-management utilities rather than image producers.

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 an explicit trigger list ('whenever the user asks to generate, create, draw, or make an image, picture, illustration, photo, artwork, or visual'), which is strong when-to-use guidance. It does not state when NOT to use it or name alternatives, but the sibling tools are unrelated so no ambiguity remains.

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