Read an image

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

Beyond the readOnlyHint annotation, the description adds meaningful behavioral details: processing happens through a local vision model, output is a verbatim transcription plus structural description, and supported image formats are specified. It does not contradict the annotations, and the local-model detail adds useful context about privacy and execution.

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?

Three sentences deliver purpose, output, supported formats, use cases, and question semantics without fluff. The most important information is front-loaded and every sentence contributes.

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?

The tool is moderately complex (vision model, multiple formats, optional question), but the description covers return values, use cases, and parameter behavior. Since there is no output schema, the description properly explains what the agent can expect. Combined with strong annotations, no critical gaps remain.

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 coverage is 100%, so the baseline is 3. The description clarifies that supplying `question` returns a focused detail instead of full transcription, but the schema already states 'Optional specific question about the image. Omit for a full description,' making this marginal added value.

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 opens with a specific verb ('Read') and resource ('local image file'), enumerates supported formats, and states the concrete output: verbatim text transcription plus structural description. This clearly distinguishes it from sibling tools like read_pdf, which handles PDFs.

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?

Explicit use cases are listed ('screenshots, error dialogs, design mockups, whiteboard photos, and graphs') and parameter usage for focused questions is described. It provides clear context for when to use the tool but does not explicitly mention when not to use it or name alternatives.

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