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

Annotations already cover readOnly, idempotent and non-destructive behavior, and the description adds meaningful context: it performs no action, returns a step-by-step procedure with screens, buttons and fields, and requires the browser tools to execute. It also mentions there is no official Midjourney API, explaining why the browser path is needed.

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 purpose is front-loaded in the first sentence, but the second sentence is a dense run-on combining the returned instructions, the no-side-effects note and the browser follow-up. The closing API claim, including the oddly future-dated 'checked 5 Nov 2026', is awkward and partly redundant.

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 zero-parameter guidance tool with no output schema, the description conveys enough: it explains the two-stage workflow and that this call only produces instructions. It leaves implicit what the agent must know before calling, such as which creation to vary.

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 tool has zero parameters, so the baseline is 4 and there is no schema semantics to compensate for. The description adds no parameter detail, which is appropriate here, though it could note which creation is meant to be varied.

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 action and resource: 'Vary creation in the user's own Midjourney account', which distinguishes it from per-creation siblings like upscale, extend_video and animate_image. However, it does not explicitly contrast itself with midjourney_upscale_creation, so sibling differentiation is only partial.

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 clear routing guidance: the tool returns step-by-step Midjourney instructions and opens nothing itself, so the agent must follow up with cotlet_browser_* tools in the user's Midjourney Cloud Browser. It does not provide explicit when-not cases or say when to prefer upscale over vary.

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