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

With no annotations provided, the description must carry the full burden of behavioral disclosure. It states the core operation (extract a page range into a new PDF) but does not disclose side effects (e.g., whether the original PDF is modified), error handling (e.g., out-of-range pages), authorization requirements, or the return format. The absence of these details leaves significant gaps for an AI agent, especially since this creates a new file, implying write operations without clarity on safety.

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 extremely concise: one sentence plus a short note. It front-loads the primary function and includes only essential detail (1-based page numbers). There is zero redundant or extraneous text, making it efficient for an AI agent to parse quickly.

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 tool that creates a new PDF from a URL with page range parameters, the description is incomplete. It does not explain error cases (e.g., invalid URL, out-of-bound pages), the output format (path, content, or binary), or any required permissions. Since there is no output schema or annotations, the description is the sole source of info, and it falls short for a multi-parameter mutation-like operation.

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 has 0% description coverage, so the description must compensate. It adds meaning for 'from' and 'to' (1-based page numbers) and context for 'url' (by URL), but it fails to explain that 'from' and 'to' are inclusive, whether they are required (schema shows 0 required), or what the URL format should be. It does not describe the output beyond 'a new PDF,' leaving ambiguity about the actual return value. These gaps mean the description only partially covers 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 clearly states the action: 'Extract a page range from a PDF (by URL) into a new PDF.' This specifies the verb (extract), resource (PDF), and scope (page range), distinguishing it from sibling tools like merge_pdf (combining documents) or pdf_page_count (counting pages). It leaves no ambiguity about what the tool does.

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 implicit guidance on when to use this tool (to extract a page range from a PDF), but it lacks explicit exclusions or alternatives. It does not mention that merge_pdf is for combining, or that pdf_rotate is for rotating pages. The instruction that 'from/to are 1-based' is a useful constraint, but there is no explicit statement of prerequisites or scenarios where this tool should not be used.

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