Read a PDF

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

The description goes well beyond the readOnlyHint annotation by disclosing the hybrid mechanism: text-layer pages are extracted exactly, while scanned pages are rendered and read by a local vision model. It also mentions the cost implication ('for free') and the optional question-based search, providing valuable behavioral context.

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 two sentences, front-loaded with the purpose, and each sentence earns its place. It is efficient and avoids redundancy with the schema.

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?

Given the tool's complexity and absence of an output schema, the description covers the main behavior and usage well. It implies the output (text transcription or answer) but does not explicitly describe the return structure. Overall, it is sufficiently complete for most use cases.

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 baseline is 3. The description adds usage examples for pages and question, but the schema already provides similar details, so the added value is marginal. It does not significantly enhance parameter understanding beyond the 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?

The description clearly identifies the tool as reading a local PDF, with a specific verb and resource. It distinguishes from sibling tools by focusing on PDFs, and explains the dual text/vision behavior, which sets it apart from read_image and vision_doctor.

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 provides clear context for using the tool (local PDFs, page selection, question-based extraction) but does not explicitly mention exclusions or alternative tools. The guidance on when to use pages and question is helpful, but it lacks an explicit 'when not to use' or alternative tool comparison.

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