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

Annotations declare a non-read-only but non-destructive, non-idempotent write; the description adds real behavioral value beyond that by disclosing cost ("Free"), that a new artifact is created, and that the returned download_url expires in about an hour. Missing only details like permissions or whether existing artifacts are untouched.

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 core content is compact, but the opening is redundant — "Build one PDF from pages of several artifacts" is restated almost verbatim in the next sentence ("Build one PDF from several artifacts"). The "Free." lead is useful but oddly front-loaded, and the trailing docs link is a reasonable close.

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?

For a one-parameter composition tool with an output schema, this covers everything an agent needs: source structure, page-range syntax, rotation options, cost, and the expiring download link. Since an output schema exists, the description is not obligated to document return values, yet it usefully summarizes them anyway.

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 0% — the single nested `sources` object has no property descriptions at all — so the description carries the full burden and does so: it defines sources as a list of {artifact_id, pages, rotate}, shows range syntax (1-3,7), states that omitting pages means every page, and enumerates rotate values (90, 180, 270). This fully compensates for the schema 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 states a concrete verb and resource — building one PDF from pages of several artifacts — and specifies page selection and rotation, which is more than a generic merge. However, it never distinguishes itself from the near-twin sibling merge_pdf (or extract_pages/reorder_pages), leaving the agent to guess which combining tool to pick.

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 only implied: the page-range and rotation options suggest this is for assembling a subset of pages across artifacts, but there is no explicit when-to-use, when-not-to-use, or named alternative (merge_pdf, extract_pages, rotate_pages). The agent must infer the selection criterion itself.

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