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

No annotations are provided, so the description must carry the transparency burden. It discloses that it uses Tesseract and supports German and English, but does not describe the return value, side effects, file access requirements, or limitations beyond language. This is comparable to the update_drive example where important behavioral context is missing.

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 a single, front-loaded sentence with no fluff. It efficiently communicates the core purpose and key details (Tesseract, languages) without wasting tokens.

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?

With no output schema and no annotations, the description should explain what the tool returns and clarify parameter usage. Both parameters are optional in the schema, but the description does not indicate whether one is required or how to choose between them. The missing usage guidance and output specification make this incomplete for reliable 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?

Schema description coverage is 100%, so the input schema already fully documents both pdf_path and pdf_base64. The description adds no additional parameter context, matching the baseline of 3 when the schema handles the parameter documentation.

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 uses a specific verb phrase 'OCR extraction' and clearly scopes the resource to 'scanned or image-based PDF invoices'. It also adds engine and language details (Tesseract, German + English) that distinguish it from siblings like invoice_parse_text or invoice_extract.

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 implies usage by mentioning 'scanned or image-based PDF invoices', which suggests it is for image-based rather than text-based PDFs. However, it does not explicitly state when to use this tool over alternatives like invoice_parse_text or invoice_from_url, nor does it mention exclusions.

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