Merge two images with AI

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

With no annotations, the description carries the behavioral disclosure burden and does disclose two key traits: it consumes credits from the configured account and returns a task id for polling (async behavior). It does not mention failure modes or rate limits, but the most consequential side effects are surfaced.

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 short and front-loaded, with the core action in the first sentence and behavioral details in the second. The website URL is slightly extraneous for an AI agent but does not undermine the overall 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?

With no output schema, the description appropriately mentions the return value (task id for polling) and cost implication. Given the sibling get_merge_status exists, an agent can infer the next step, though a brief mention of checking status via that tool would make it fully complete.

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%, so the baseline applies; all four parameters are already documented in the schema. The description adds only the 'public' and 'exactly two' constraints, which are also present in the schema, so it provides no significant meaning beyond it.

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 action ('Combine exactly two public JPG, PNG, or WebP image URLs') and a clear result ('into one AI-generated image'). It does not explicitly name the sibling get_merge_status, but the note about returning a task id for polling signals the async workflow and helps differentiate it from status polling.

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?

Clear context is provided: the tool is for merging two public image URLs, with prerequisites explicitly mentioned (public, supported formats, exactly two). It omits explicit when-not-to-use guidance, but with only one sibling (a status poller), the usage context is sufficient.

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