upload_reference_image

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

The description adds useful behavioral details beyond the annotations: automatic compression, size limits (max 2MB, max 2048px), and that it returns a public URL. Annotations already indicate destructiveHint=true (mutation), but the description clarifies what the mutation does. No contradictions with annotations.

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 three short sentences with no wasted words. The first sentence immediately conveys the core purpose, and subsequent sentences provide necessary constraints and usage guidance. Ideal conciseness.

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 simple upload tool with one parameter and no output schema, the description covers purpose, constraints, and return type (public URL). It could be slightly more explicit about the return format, but the information provided is sufficient for an agent to use the tool correctly.

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% coverage with a thorough description of the filePath parameter, including accepted formats and behavior. The tool description adds no new parameter-level semantics beyond restating the purpose, so a baseline of 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 verb 'upload', the resource 'local image', and the purpose 'for use as a reference in generate_image'. It distinguishes itself from sibling tools like generate_image by focusing on the upload step.

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 explicitly states 'Call this when the user wants to use a local file as a reference image.' This provides clear guidance on when to use the tool. However, it does not mention alternative scenarios (e.g., using a URL directly in generate_image) or when not to use it.

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