Merge local PDFs

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

Annotations already indicate this is a local, non-read-only, non-idempotent operation. The description adds useful behavior beyond that: input-order preservation, input limits, output verification, and caveats that metadata/attachments may be omitted and signatures invalidated. It still omits overwrite/error behavior for output_path.

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?

Three sentences, front-loaded with the core action and constraints, then behavioral caveats. Every sentence adds useful information with no filler.

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?

The description is strong on limits and caveats, and annotations cover safety, but it does not explain keep_bookmarks, overwrite behavior for output_path, or what is returned after verification. For a 3-parameter mutation tool with no output schema, that leaves notable gaps.

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 coverage is only 33%, and keep_bookmarks has no schema description and is never mentioned in the description. The description clarifies input ordering and aggregate limits, but it fails to explain a full third of the parameters, leaving a material gap.

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 uses a specific verb and resource: 'Combine ... PDFs ... into a new PDF.' It also scopes the operation to 'unencrypted local PDFs in input order,' which clearly distinguishes it from split, select, and images-to-PDF siblings.

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 clear applicability constraints: 2 to 32 unencrypted local PDFs, with size and page limits. It does not explicitly name alternative siblings or when-not conditions beyond rejecting encrypted/non-local inputs, so it falls short of full routing guidance.

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