Merge PDFs into one file

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

Adds real behavioral context beyond annotations: inputs are never modified, page sizes are kept as-is (mixed sizes possible), and the result reports that. Free-tier cap of 5 files is disclosed. Annotations already state destructiveHint=false and readOnlyHint=false; description reinforces the non-destructive behavior of inputs.

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 tight sentences: action and ordering first, then output behavior (mixed sizes), then input safety and limit. Zero waste and well front-loaded.

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?

Covers action, ordering, output quirk (mixed page sizes), input immutability, and a service limit. No output schema exists, but the description says the answer reports page-size mixing. Missing explicit overwrite guidance, though the schema covers it fully.

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 100%, so paths, out_path, and overwrite are already documented with semantics including default false for overwrite. The description only mentions ordering of inputs, which duplicates the paths description. Baseline 3 is appropriate.

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 (join/merge) and resource (PDFs) with the ordering scope ('in the order given'). An agent can distinguish it from pdf_split, pdf_reorder, and other pdf_* siblings without opening schemas.

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?

Implies usage ('join several PDFs into one') but offers no explicit when-to-use vs alternatives like pdf_reorder or pdf_split. The free-tier limit is a useful constraint but not a usage routing rule.

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