describe_image

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

With no annotations, the description carries the full burden. It discloses the return format ('Returns: A text description of the image') and the action itself, but does not mention any limitations, potential errors, or processing behavior beyond that. It is adequate for a simple read-only tool but lacks richer behavioral context.

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 well-structured with Args, Returns, and Examples sections. It is concise (about 10 lines), every line adds value, and examples illustrate usage clearly. No redundant or filler content.

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 simplicity (2 params, no annotations) and the presence of an output schema (though not shown), the description covers all needed aspects: purpose, when to use, parameter semantics, return value, and examples. It is complete for an agent to invoke correctly.

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 fully compensates. It explains image's format ('file path, URL, or base64') and detail_level's options and default ('brief', 'detailed', 'exhaustive'). This adds significant meaning beyond the bare schema property definitions.

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 action ('Generate a text description of an image') and its purpose (caption, alt text, general summary). It differentiates from sibling tools by emphasizing 'without asking a specific question,' which distinguishes it from more query-specific tools like analyze_chart or extract_text.

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 when-to-use guidance: 'Useful when you need a caption, alt text, or a general summary.' It also implies when-not-to-use by saying 'without asking a specific question,' but it does not explicitly name alternative tools as in the high-calibration example.

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