Upload file to Gemini Files API

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

Annotations (readOnlyHint=false, openWorldHint=true) already indicate a mutating, side-effectful operation. The description adds the outcome of returning URI and metadata but lacks details on permissions, error handling, or specific behavioral traits beyond what annotations provide.

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 two sentences long, front-loaded with the core purpose, and the second sentence adds a valuable usage hint. Every sentence is purposeful and there is no unnecessary information.

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 no output schema, the description adequately states the return type (URI and metadata). It covers the tool's purpose and usage context. Minor gaps exist regarding file type restrictions or error handling, but overall it is fairly complete for a simple upload 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?

The input schema has 100% parameter description coverage, so the baseline is 3. The description does not add meaning beyond what the schema provides; the mention of 'image' in the usage hint slightly conflicts with the general 'file path' parameter, but not severely.

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 verb 'upload', the resource 'local file through the Gemini Files API', and the outcome 'return its URI & metadata'. It effectively distinguishes from sibling tools like generate_image and maintenance, which have different purposes.

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 provides a specific use case: 'Useful when the image is larger than 20MB or reused across prompts.' This gives clear context for when to use the tool, though it does not explicitly state when not to use it or provide alternative tools.

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