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

Beyond the annotations, the description discloses two non-obvious behaviors: pages are 1-indexed, and in reorder mode any page left out is dropped (a data-loss consequence the agent must warn about). It does not mention whether the source file is preserved or what the output is, but the annotations plus output schema cover part of that.

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?

One front-loaded sentence with the resource and indexing rule first, then the operations. The nested parentheticals get slightly dense, but no clause is filler — each maps to a distinct operation.

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 an 8-parameter, 4-mode tool with a nested file object and an output schema, the description covers the operation semantics and the 1-based indexing that are the main sources of misuse. The three file-input variants (file_id, file_url, library_file_id) are left entirely to the schema, which is acceptable given their descriptions.

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?

With 75% schema coverage the baseline is 3, and the description earns an extra point by tying parameters to operations — `pages` means targets for delete/keep but the full ordered list for reorder, and rotate operates on all pages or a range. `angle` is still only defined by its enum in 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?

States a specific verb (change pages) and resource (a PDF), then enumerates all four operations the `operation` enum supports: delete, keep, reorder, rotate. That enumeration is what separates it from siblings like split_pdf, merge_pdfs, or compress_pdf, which each do a different page-level job.

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 operation list implies when the tool is appropriate, but there is no explicit routing: nothing says 'use split_pdf instead if you want separate files' or 'use this when page targets are from the 1-based index'. Usage is inferable from the operation names rather than stated.

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