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

Annotations already indicate this is not read-only and not destructive. The description adds behavioral details beyond that: it clarifies the output format (returns a file_id + URL per part) and the default behavior (one per page). It does not discuss side effects on the original file or any auth/rate limits, but given the simple nature, this is sufficient.

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, information-dense sentence. It front-loads the core purpose, includes the default behavior, a range example, and the return format, with zero filler. It is well-structured and easily parseable.

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 straightforward tool, the description covers all essential aspects: the operation, the default behavior, the range syntax, and the output format. The schema covers parameters, and there is no output schema, but the description explicitly states what is returned. No critical information is missing for an agent to invoke it correctly.

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%, and the description does not add substantial meaning beyond the schema. It reiterates the range format and the default behavior, which are already in the schema descriptions. Since the schema fully documents parameters, a baseline of 3 is appropriate; the description adds marginal value.

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 the action 'split', the resource 'a PDF', the output 'multiple PDFs', and gives the default behavior plus an example of page ranges. It is clearly distinct from siblings like merge_pdfs and select_pages, which perform different operations.

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 context (splitting a PDF) and shows the range syntax, but it does not explicitly mention when to use this tool instead of alternatives, nor does it state any exclusions or prerequisites. The sibling set includes select_pages, which might overlap, but no differentiation is provided.

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