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

No annotations are provided, so the description carries the burden. It discloses that inputs can be base64 or URLs and the output is base64. It does not mention non-destructiveness, error handling, or size limits, but for a simple merge, these are not critical gaps. The transparency is good.

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 sentence, front-loaded with the main purpose. Every word contributes meaning, with no wasted space.

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?

Given the tool's simplicity, the description covers core functionality (merge, order, output format). It does not discuss edge cases or return format details beyond base64, but with no output schema, this is sufficient. Sibling tools provide context that it is one of many PDF operations.

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 input schema already describes the 'pdfs' parameter as an ordered list of base64 strings or https URLs. The description adds no new meaning beyond the schema, so it meets the baseline but does not exceed it.

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 tool merges two or more PDFs into one, preserving order, and returns the result as base64. This distinguishes it from sibling tools like compress_pdf, split_pdf, etc., which have different functions.

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 indicates the input order matters, implying when to use it (combining PDFs in a specific order). However, it does not explicitly state when not to use or compare with alternatives like split_pdf. The guidance is clear but not exhaustive.

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