Merge PDFs

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

Beyond the annotations, the description discloses important behavioral traits: the operation runs locally using pdf-lib, nothing is uploaded, no URL is fetched, and existing output files are preserved unless overwrite is true. This gives an agent meaningful safety and side-effect information that annotations alone do not provide.

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 compact and front-loaded: the primary action is stated first, followed by local-execution context and overwrite safety. Every sentence contributes useful information without repeating schema details.

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 output schema and annotations, the description covers what an agent needs to call the tool correctly: input order, local execution, no upload, and protected overwrite behavior. It is sufficiently complete for a moderately simple file-merging tool.

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 the schema already documents all three parameters. The description adds value by clarifying that paths refer to local files, that no URL is fetched, and that overwrite behavior is guarded. Since it enriches the schema's parameter meaning with local-only semantics, it earns credit above the baseline.

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 opens with a clear verb and resource: 'Combine two or more local PDFs into a single file, in the order given.' It unambiguously describes what the tool does and distinguishes it from siblings like pdf_info, extract_pdf_pages, and clean_text, all of which have different purposes.

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 clearly states the intended use case: merging multiple local PDFs into one file. It also provides relevant context such as local execution and order preservation. It does not explicitly name alternatives or say when not to use the tool, but the core usage context is clear and the sibling tools are sufficiently distinct.

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