Merge PDF

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

Annotations already declare the safety profile (destructiveHint=false, readOnlyHint=false, idempotentHint=true), so the bar is lower. The description adds that input order is preserved and that file count is unbounded, but it omits the important non-overwrite constraint and any failure behavior, which the schema carries instead.

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?

Two short sentences, front-loaded with the action, with no redundant or filler content. Every clause contributes either the operation, the ordering rule, or the size constraint.

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?

An output schema exists so return values need no explanation, and annotations cover the mutation safety profile. The description plus schema give an agent enough to call the tool correctly; only edge behavior on missing/unwritable paths is left implicit.

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%, so both parameters are already documented, including the ordering of 'inputs' and the non-overwrite rule for 'output'. The description only restates the ordering ('in the order given') and adds the unbounded-count detail, so 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 and resource ('Combine ... PDFs ... into one new PDF') plus the ordering semantic, so the operation is unambiguous. It does not name or contrast any sibling, but merge is unique among the listed tools so confusion risk is low.

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?

Usage is implied by the operation itself ('combine 2 or more'), and the 'no upper limit' note hints at scale. There is no explicit when-to-use versus alternatives (e.g. pdf_extract_pages, pdf_split, pdf_from_images) and no mention of the preconditions such as the output file not existing.

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