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

The description adds 'Deterministic, $0.002', which is not in annotations, and clarifies that it creates a new PDF (non-destructive). Annotations already include idempotentHint and destructiveHint, so the description adds value by specifying determinism and cost, though it doesn't detail error handling or authentication requirements beyond the schema.

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 concise sentence that front-loads the action and output, followed by a brief note on determinism and cost. There is zero redundancy, and every phrase serves a purpose.

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?

For a relatively simple tool with no output schema, the description adequately indicates the output (a new PDF) and mentions cost/determinism. It does not specify the exact return structure (e.g., URL vs. file) or potential edge cases, but given the tool's simplicity and the presence of schema descriptions, it is sufficiently complete.

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% with descriptions for all three parameters. The tool description reiterates '1-based ranges' but adds no new meaning beyond the schema. The description does not elaborate on 'url' or 'x_payment' beyond what schema provides, so it adds minimal value in parameter semantics.

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 states a specific verb ('Extract'), a resource ('pages from a PDF'), and the output ('a new PDF'). It clearly differentiates from siblings like pdf_merge (merging) and pdf_info (information extraction) by focusing on page-range extraction.

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 (extract specific pages) but does not explicitly contrast with alternatives or state when not to use it. It lacks explicit routing guidance such as 'use pdf_merge for combining PDFs' or 'use pdf_info for metadata'. The intended use case is clear, but no explicit when/when-not guidance is provided.

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