blender_render_image

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

The description discloses blocking behavior, return format (metadata JSON plus inline PNG preview), and disk saving when output_path is given. It also explains engine override and sample override side effects. With annotations being false for all hints, the description carries the burden well, though it doesn't mention if the scene's frame is temporarily changed or other subtle state mutations.

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 well-structured with a one-line summary, followed by behavioral notes, parameter summary, return explanation, and two clear examples. No word is wasted; every sentence adds value. It is appropriately sized for a tool of this complexity.

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?

Given the moderate complexity (6 parameters), no output schema, and weak annotations, the description covers all essential aspects: what it does, blocking behavior, engine guidance, return format, optional disk saving, and usage examples. The agent has enough context to invoke the tool correctly and interpret results.

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?

Despite the schema coverage being 0% (as signaled), the description lists all parameter categories: frame, output_path, engine override, Cycles sample override, preview size, and timeout. It adds usage depth by noting that CYCLES is slower and to increase timeout_seconds, and provides concrete examples showing how parameters are passed. It doesn't restate types or constraints, but the examples and high-level summaries compensate for the schema gap.

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 opens with a specific verb and resource: 'Render a frame using Blender's render engine and return the result inline.' It clearly distinguishes from siblings like blender_get_viewport_screenshot by specifying rendering via Blender's engine. The inline result behavior and full-resolution save option further clarify its scope.

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 description provides explicit guidance on engine choice ('For fast previews use EEVEE; for photorealistic output use CYCLES (much slower — increase timeout_seconds)') and notes that the tool blocks until render completion. It doesn't explicitly state when not to use it or name alternatives, but the context is sufficient for an agent to select it appropriately.

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