Upload a reference image

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

Adds substantial behavior beyond the annotations: per-key rate limits (60/min, 1,000/day), public visibility of the uploaded copy, 72-hour automatic deletion, and the user-consent constraint. These are exactly the side effects an agent needs to judge before calling a non-idempotent write.

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?

Four dense sentences, front-loaded with capability and return value, then constraints, then cost/limits, then safety caveat. No filler and nothing repeated from the schema.

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?

Covers formats, size limit, return value (compensating for the absent output schema), the either/or input rule, rate limits, retention, and privacy. Nothing an agent needs in order to call this 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 coverage is 100%, so the baseline would be 3, but the description adds the mutual-exclusion rule (exactly one of path or url) that the schema cannot express given zero required parameters and no oneOf. The parenthetical 'a local file the user named' also adds consent semantics to path.

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 (upload an image), names accepted formats and the 10 MB cap, and specifies the output (a public https://img.apiko.app URL). It also names the destination reference fields, which clearly separates it from siblings like generate_image or generate_video.

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?

Gives concrete conditions: supply exactly one of path or url, and only upload files the user explicitly asked to use. It implies the context (populating reference fields) but never names an alternative tool such as generate_image, so the when-not is only partially covered.

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