read_image_text

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

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint), the description discloses important behavioral traits: it requires Tesseract-OCR, it is OCR not vision (so it does not understand image meaning), and it may return empty results for text-less images, with next_actions explaining why. This adds significant value over annotations.

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 and front-loaded with the core purpose, followed by usage guidelines, return details, and examples. It is slightly verbose with the examples, but each section carries useful information without redundancy.

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 OCR tool, the description covers purpose, usage, limitations, and dependencies. The output schema is mentioned (though not shown) and the max_chars truncation is addressed. The only minor gap is that it could specify what happens on file-not-found or unsupported formats, but these are likely covered elsewhere.

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%, with both parameters clearly described (file_path as absolute path, max_chars as truncation limit). The description itself does not add further parameter detail, so per the calibration baseline of 3 for high coverage, this score is appropriate.

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 specifies the exact verb and resource: 'Reads a PNG image with OCR to extract text' and explicitly distinguishes it from read_document for document formats. It clearly states the tool's scope and what it does not do.

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 explicitly states when to use the tool ('for screenshots, scanned notes, labels on diagrams') and when not to use it ('for pdf/docx/pptx/svg documents → read_document'), providing clear exclusions and routing to alternatives.

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