Generate still images (free)

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

Annotations already indicate non-idempotent, non-destructive write. Description adds valuable context: 'costs ZERO credits', 'downloads results', 'returns local file paths'. No contradiction 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?

Two sentences, 35 words. Every sentence adds value: purpose, cost, usage guidance, output format. No redundancy.

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 purpose, behavior, usage context, and output. Lacks mention of prerequisites (e.g., open project) or error handling, but sufficient for a simple tool with good annotations.

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 covers 67% of params with descriptions; description adds minimal new meaning beyond schema. The 'full composition prompt' hint is already in schema. No param-specific elaboration.

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?

Specifically describes generating still images, emphasizes zero credit cost, and explicitly frames it as a composition sandbox before video. Differentiates from sibling `flow_generate_video` by cost and iteration purpose.

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?

Explicitly advises 'always compose in stills before spending anything on video', providing clear when-to-use guidance. Does not explicitly state when not to use but context implies avoiding for final output.

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