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

No annotations are provided, so the description carries the full burden and fully meets it: it discloses best-effort accuracy, misreads under blur/skew/contrast, no layout preservation, paid compute with a 20-calls/hour/IP cap, and the upload restriction that third-party URLs are rejected. This is exceptionally transparent for a tool with no annotation coverage.

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?

One dense paragraph, front-loaded with the core usage condition and then covering limitations, quota, and URL handling without redundancy. Every sentence contributes a distinct fact an agent needs to invoke this correctly.

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?

Despite having no annotations and no output schema, the description tells the agent the return shape ({ text, language, confidence? }), failure modes, quota, and the exact way to supply the image via a razi.pro-storage URL. The only incompleteness is that fileUrl is described but missing from the input schema, which could confuse schema-driven invocation.

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 schema already fully documents language (100% coverage), and the description adds the important operational caveat that one language per call is allowed and naming the wrong one degrades accuracy. It also documents fileUrl in prose, but that parameter is absent from the input schema, so the guidance is helpful yet not aligned with the structured schema.

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 precise verb and resource: it runs OCR on images and returns a best-effort transcription, explicitly contrasted with parse_document. The phrase 'Use this ONLY when the text exists as PIXELS' makes its job unmistakable and distinguishes it from sibling tools.

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 when-to-use ('text exists as PIXELS') and when-not-to-use conditions ('If the file already stores real characters, this is the wrong tool'), names the exact alternative (parse_document), and provides a robust deciding heuristic: 'what the bytes contain, never the file extension'. It also adds rate-limit and payment context for operational selection.

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