Merge PDFs

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

Annotations already provide readOnlyHint, destructiveHint, idempotentHint, and openWorldHint, establishing this as a safe, non-destructive operation. The description adds value beyond annotations by specifying that page order is preserved and that the result is a temporary download URL (API2PDF). This extra context helps the agent understand the output lifecycle.

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 consists of three short, front-loaded sentences: the main action, a behavior note (page order), and the output type. Every sentence adds essential information with no redundancy or unnecessary words.

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 presence of output schema, and annotations covering safety, the description adequately covers the required information. It explains input constraints (2-20 PDFs by URL) and output (temporary download URL). Minor missing detail like URL accessibility or temporary URL duration, but overall complete for a merge 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% (both parameters have descriptions). The tool description reiterates that URLs are provided as input and mentions the output filename indirectly (via the purpose), but does not add significant new semantics beyond the schema. 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?

The description uses a specific verb 'Merge', identifies the resource 'PDF documents (provided as URLs)', and states the output 'single combined PDF' with a temporary download URL. It clearly distinguishes from sibling tools like document.convert.to_pdf or document.pdf.from_html, as these perform different operations (conversion/generation) rather than merging multiple PDFs.

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 implies usage for merging 2-20 PDFs into one, but it does not explicitly state when to use this tool over alternatives, nor does it mention any prerequisites or exclusions. The purpose is clear enough for agents to infer, but lacks explicit guidance on when not to use it.

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