blender.render

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

With zero annotations, the description carries the full burden and does reasonably well: it discloses the return values, warns that "Render time grows quickly with resolution and samples," and clarifies that omitted args preserve current scene settings (implying overrides may mutate scene state). It stops short of stating whether the call blocks or what permissions/preconditions apply.

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?

Front-loaded purpose sentence followed by tightly formatted per-parameter notes and a closing perf tip; every line earns its place. Slightly verbose but no padding.

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 5-param, all-optional render tool with an output schema and no annotations, the definition covers parameters, defaults, side-effect-preserving omissions, and cost trade-offs. The main gap is routing guidance versus blender.render_preview and confirmation of blocking/async behavior, but the return values are covered by the output schema.

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 0%, so the description must compensate and it does: each of the 5 params gets real semantics — engine ids with an example and a pointer to blender.get_scene, resolution units in pixels, samples behavior (ignored by non-sampling engines), and output_path path conventions. This is meaningful context well beyond the schema's bare anyOf/null types.

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+resource ("Render the active scene with the current camera") and even names the return payload (output path and wall-clock render time). It is clear on its own, but it never mentions the sibling blender.render_preview, so an agent must infer which of the two rendering tools to pick.

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 perf note ("prefer 512-1024 px while iterating") and the per-parameter "Omit to keep..." defaults imply a usage posture, and the engine note routes to blender.get_scene for valid ids. However there is no explicit when-to-use or when-not-to-use guidance and no comparison against blender.render_preview, which is the obvious alternative.

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