understand_image

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

No annotations are provided, so the description carries the transparency burden. It clearly identifies the underlying model (Gemini 2.5 Pro vision), frames the operation as non-destructive Q&A, and states that both local paths and URLs are accepted. It does not discuss size limits or privacy implications, but there are no destructive or auth-related side effects to disclose.

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 two sentences with no filler. It front-loads the core purpose, follows with concrete use cases, and ends with accepted input formats. Every sentence earns its place.

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 simple two-parameter vision Q&A tool with no output schema, the description covers the main invoke-time needs: what it does, which model powers it, accepted input sources, and common use cases. It could explicitly state that the response is text and that question is optional, but those are already implied by the wording and 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?

The input schema already documents both parameters with 100% coverage, so the description adds little parameter-level meaning beyond reinforcing that this is question-driven and can produce a detailed description. The baseline of 3 is appropriate because the schema carries the load.

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 uses a specific verb and resource ('Ask questions about image content') and enumerates concrete task types: extract text, identify objects, describe products, check quality, get detailed descriptions. This clearly distinguishes it from the sibling image generation/editing tools like generate_image and crop_image_to_square.

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?

It gives clear context for when to use this tool: any time the agent needs to understand, inspect, or describe an image rather than modify or generate one. It does not explicitly say 'do not use for editing', but the description and sibling set make that boundary obvious.

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