list_input_files

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description goes well beyond them: it explicitly says the tool does not read content, import, or upload, and clarifies that size compliance does not prove format/page-count validity or constitute user authorization. These boundary disclosures are the kind of context annotations cannot express.

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 dense but front-loaded: purpose and scope come first, followed by caveats, pagination, and the sibling pointer. Every clause adds signal, though the caveat cluster ('does not read/import/upload' plus the validity and authorization disclaimers) is slightly heavy for the amount of behavioral difference it conveys.

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 (covering next_offset), and annotations cover safety, so the description need not explain return values. Given full context, it supplies trigger conditions, scope limits, non-actions, pagination behavior, and the alternative tool – nothing an agent needs to invoke it correctly is missing.

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 0%, so the description carries the burden. It explains pagination via next_offset and first-page refresh, but never defines the offset or limit parameters themselves (e.g., units, max limit, default of 20), so it only partially compensates for the coverage gap. 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 states a specific verb (paginated list) and resource (first-level PDF/JPG/PNG candidates in the configured input directory) with explicit scope constraints. It names the sibling list_documents as the alternative for already-imported materials, so an agent can distinguish it without opening a schema.

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?

It states the trigger scenario (user wants to view materials pending import) and the exclusion/alternative (use list_documents for imported materials). It also explains the pagination workflow (continue with next_offset, refresh the first page when the directory changes) and warns that actual import still requires per-file checks.

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