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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the safety profile is covered. The description adds the alternating-page behavior, but it does not disclose output details or side effects beyond the operation itself, which is acceptable given the annotations.

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 short and front-loaded, with only minor redundancy: 'Interleave PDFs — Interleave pages' repeats the title. The added detail about alternating pages and double-sided scans earns its place.

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 simple one-parameter tool with clear annotations, the description is sufficient to select and invoke it correctly. It explains the core operation and a motivating use case, though it does not explicitly describe return values or contrast with pdf_merge.

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%: the files parameter already states 'PDF (exactly 2 files).' The description's mention of 'two PDFs' reinforces but does not add meaning beyond 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?

The description names a precise verb ('Interleave'), the specific resource ('pages from two PDFs'), and the exact behavior ('alternately'). It clearly distinguishes this tool from a plain pdf_merge, since alternating page order is an operationally different action.

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?

It provides a clear use case: 'useful for double-sided scans.' However, it does not explicitly mention when not to use it or name an alternative such as pdf_merge for simple concatenation.

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