generate_image

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 effectively describes key behavioral traits: synchronous operation ('Blocks until the file is on disk'), typical latency ('under 10 seconds'), file handling ('PNG is written to OUTPUT_DIR'), and return value ('absolute path is returned'). It also notes model-specific behavior differences (e.g., negative_prompt ignored by Nano Banana). However, it lacks details on error handling or rate limits.

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 appropriately sized and front-loaded: the first sentence states the core purpose and key behavioral trait (synchronous blocking). Subsequent sentences efficiently cover latency, output details, and parameter explanations in a structured format with bullet-like clarity. Every sentence adds value without redundancy.

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?

Given the complexity (image generation with multiple parameters), no annotations, and the presence of an output schema (which handles return value documentation), the description is complete enough. It covers purpose, behavior, parameters, and output location, leaving the output schema to detail the return structure. No critical gaps remain for agent understanding.

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 fully compensate. It provides comprehensive parameter semantics: 'prompt' as the text description, 'model' with two options and cost/quality trade-offs, 'aspect_ratio' with five specific options, and 'negative_prompt' with optional usage and model-specific behavior. This adds significant meaning beyond the bare schema, fully documenting all four parameters.

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 clearly states the tool's purpose: 'Generate an image synchronously' with specific details about the output format (PNG) and location (OUTPUT_DIR). It distinguishes from sibling tools like 'list_images' (which retrieves existing images) and 'submit_video' (which handles video generation), making the verb+resource combination specific and differentiated.

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 provides clear context for when to use this tool: for synchronous image generation with latency under 10 seconds. It distinguishes from alternatives by specifying the output format (PNG) and location (OUTPUT_DIR), but does not explicitly state when NOT to use it or compare it to other image-related tools beyond the sibling list.

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