read_pdf

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

While annotations already mark the tool as read-only, idempotent, and non-destructive, the description adds substantial behavioral context beyond these hints. It discloses the page-by-page return structure, the 200-page hard limit, the default of 50 pages, unsupported encrypted PDFs, and the required configuration file setting. This is exactly the kind of context an agent needs for safe and correct invocation.

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?

Four sentences, each adding value: purpose, when-to-use, limits/default, and constraints/prerequisites. The most critical information is front-loaded, with no filler or repetition of schema content.

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?

The description covers purpose, usage scenarios, limitations, and configuration requirements. With only two well-documented parameters, strong annotations, and no output schema, the description is fully sufficient for an agent to select and use this tool correctly. Sibling tools are clearly distinct.

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 schema already fully documents both path and max_pages with descriptions and defaults. The description's mention of 'pass max_pages for larger documents' is a mild usage hint but does not add significant semantic meaning beyond the schema. Thus baseline 3 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 opens with a specific verb and resource: 'Extract text from a PDF file.' It further clarifies the page-by-page return format, which is a concrete behavioral detail. This clearly distinguishes it from sibling tools like read_file or read_document, which could also handle files.

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 an explicit 'Use this when' clause covering read, summarise, or answer questions scenarios. It also mentions the page limit and encrypted PDF limitation, giving clear context for when to use the tool. However, it does not explicitly name alternatives or state when NOT to use it, so it doesn't quite achieve a 5.

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