Describe Image

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

Annotations only include openWorldHint=true, leaving the description with the main burden. It mentions provider dependency for image_url ('support depends on the configured provider/model') and hints at performance with focused prompts, but does not disclose potential limitations (e.g., image size, errors, or untrusted-source banner details). No contradiction with annotations, but limited behavioral disclosure.

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 a single, tight paragraph with no filler. It front-loads the core purpose and then gives practical usage tips. Slightly dense but efficient.

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 tool's complexity (8 parameters, no output schema), the description outlines capabilities and gives usage guidance but does not explain return formats (except via schema) or edge-case behavior. Since the schema covers parameter details and output_format, this is adequate but not rich. Missing information about size limits or error handling keeps it at a 3.

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. The description adds minimal extra meaning: it emphasizes focused prompts and repeats schema guidance for image input methods (e.g., 'Use image_base64 or image_ref when URL input is unavailable'). It does not significantly enhance parameter understanding beyond the schema.

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 with specific verbs and resources: 'See and understand images — screenshots, photos, diagrams, charts. Extract text (OCR), describe scenes, compare images, and answer questions about what is shown.' It distinguishes from alternatives by listing the input methods and capabilities.

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?

Explicitly states when to use: 'Use whenever an image is provided via image_path, image_url, image_base64, image_ref, or images[].' Also provides guidance on how to phrase prompts for better results ('ask the specific question... instead of an open-ended...'), which is actionable usage direction.

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