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

Goes well beyond the annotations: discloses the returned fields, the 422 failure modes and that failures aren't charged, typical latency (1-5 s), price and free quota, plus a prompt-injection warning on untrusted extracted text. The only reason this isn't a 5 is that retry/idempotency behavior and rate-limit handling beyond the free tier are left implicit.

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?

Front-loaded with purpose and sibling routing, then progressively discloses outputs, errors, cost, and trust caveats. Dense but nearly every clause is load-bearing; the pricing/quota and docs-link tail makes it longer than strictly needed for tool selection.

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?

A read-only, open-world, single-URL OCR tool with full schema coverage and an output schema. The description covers success output shape, failure modes, cost, timing, and data-trust posture — nothing an agent needs to invoke it correctly is missing.

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 url formats, size limits and Tesseract lang codes are already fully documented in the schema. The description adds only the marginal fact that unsupported languages yield a 422, which is the correct baseline-3 outcome when the schema does the heavy lifting.

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?

States a specific verb and resource ('OCR the text in a public image') and immediately distinguishes itself from pdf_ocr and read_qr_barcode, so an agent can route correctly without opening any schema.

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?

Gives explicit alternative routing: scanned PDFs go to pdf_ocr, QR/barcodes go to read_qr_barcode. It also enumerates the conditions that produce a 422 (non-images, oversize, unsupported languages, private addresses), which effectively defines when not to call it.

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