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

Annotations already establish the safe read-only, idempotent profile, so the bar is lower. The description adds real context: the output is a single inline image, rendering carries no cost, and the result is meant to be handed to the user for editing. It stops short of describing failure modes when no completed run exists.

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?

Three tight sentences with the operation and its precondition front-loaded and no filler. Each sentence contributes (scope, cost, downstream handoff).

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 usefully notes the return is one inline image and gives the intended user handoff, covering most of what the agent needs. The unexplained 'projectUrl' reference is the one loose end in an otherwise complete picture.

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 schema carries parameter meaning and 3 is the baseline. The description's 'up to four' merely restates the maxItems constraint, and it references a 'projectUrl' to send alongside the image that does not correspond to any parameter in the schema, which adds noise rather than clarity.

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 ('Render up to four project screens as one inline image'), includes the scope cap and the precondition ('after a design run completes'). An agent can distinguish this from siblings like get_component or design without opening the schema.

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 condition 'after a design run completes' gives implied timing, and the four-screen cap implies batching, but no alternative tool is named and no explicit when-not guidance is provided. Adequate but leaves routing to inference.

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