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

Annotations already declare readOnlyHint/openWorldHint/idempotentHint and destructiveHint=false, so safety is covered. The description adds genuinely useful context beyond that: each result carries a direct public-domain download URL plus file type and size, telling the agent what it will receive. It does not say what happens when a record has no digitised files.

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 compact sentences: what it returns, when to use it, and a worked example call. The scoping of the resource is front-loaded and every sentence earns its place.

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?

No output schema exists, but the description compensates by naming the per-file return fields — download URL, file type, size. Combined with the schema's limit bounds, an agent has everything needed to call this correctly and interpret the result.

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 naid and limit are already documented in the schema. The description reinforces naid by tieing it to the record whose scans you want and shows a sample value, but adds no syntax or format detail beyond the schema. Baseline 3 applies.

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 — list the digitised files attached to one NARA Catalog record — and enumerates the media types returned (scanned images, PDFs, audio, video). It is clearly distinguishable from nara_search and nara_record, which return descriptions rather than the files themselves.

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?

Explicitly says to use this after nara_search or nara_record when the goal is the actual document rather than its description, naming both alternatives and the condition that selects this tool. Nothing is left to inference.

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