ocr_region

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

With no annotations provided, the description carries the full burden and does a solid job. It discloses the coordinate system ('device pixels'), the output format (JSON array of objects with fields), and that results are 'relative to the crop region.' It doesn't address potential side effects or edge cases, but for a read-only OCR operation this is fairly transparent.

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 composed of three short sentences, each adding distinct value: purpose, advantage, and output format. There is no redundant or filler content, making it both concise and structured.

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 relatively simple, and the description covers the essential aspects: what it does, the coordinate system, a performance note, and the exact output structure. The output schema also exists to detail the return value. Missing are edge cases like coordinate bounds or error handling, but these are not critical for basic use.

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 has no per-parameter descriptions (0% coverage), so the description must compensate. It adds 'Coordinates in device pixels,' which gives the unit but not the exact meaning of x1, y1, x2, y2 (e.g., bounding box corners). The 'device' parameter is left to the context of sibling tools. This is partially helpful, but not fully clarifying.

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 a specific verb-object pair: 'OCR a specific region of the screen.' It distinguishes itself from the sibling tool 'ocr_screen' by explicitly targeting a region, and the additional note 'More accurate than full-screen OCR' further clarifies its unique value.

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 implicitly provides usage guidance by stating it is 'More accurate than full-screen OCR for targeted text extraction,' which tells when to prefer this tool over an alternative (ocr_screen). However, it doesn't explicitly mention when not to use it or list other alternatives, so it's clear but not exhaustive.

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