gemini_list_files

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description doesn't need to restate safety. It adds valuable behavioral context: retention is ~48h, so vanished entries have expired rather than failed, and it discloses that results include file_uri, MIME types, and expiry times. This goes beyond the annotations and helps the agent interpret results correctly.

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?

Two sentences, front-loaded with the core purpose and scope, followed by a useful retention caveat. No wasted words; 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?

For a read-only list tool with one optional parameter and no output schema, the description is nearly complete. It explains what is returned (file_uri, MIME types, expiry times) and how to interpret missing entries. It doesn't describe pagination or the exact response format, but those are minor given the tool's simplicity and the annotations covering safety.

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% for the single optional page_size parameter, so the schema already documents it fully. The description doesn't add parameter-specific details, but with full coverage, 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 clearly states the tool lists files, images, and photos uploaded to the Gemini Files API under the current API key, and distinguishes it from other operations by mentioning reusable file_uri references, MIME types, and expiry times. It uses a specific verb ('List') and resource ('files... under this API key'), making it easy to differentiate from siblings like gemini_upload_file and gemini_delete_file.

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 when to use this tool: to check currently uploaded files and their references, and clarifies that missing entries mean expiry rather than failure. It doesn't explicitly name alternatives or exclusions, but the context is clear enough for an agent to select it over upload/delete/get_result tools.

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