render

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

With no annotations, the description carries the full burden and does well: it discloses the returned manifold report (simple, volumes, facets), the extra bounding box and volume for STL, that png output is retained rather than returned, and that full_render is slower but evaluates real geometry (mattering for cut/differenced models). It does not mention permissions, overwrite behavior, or timeout handling, leaving a few behavioral gaps for a mutation-style tool.

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 with the core purpose and format rule, then returns, then the sibling comparison, then view options — a sensible order. The paragraph is on the long side with a few discursive phrasings, but nearly every sentence carries information an agent needs.

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?

An output schema exists, so return values need not be described (though the description does so anyway, usefully). However, for a 12-parameter tool with only one required parameter, the description omits how to supply the input script/model (file, source, defines), image sizing (imgsize), and timeouts — real gaps an agent must resolve from the schema alone.

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 covers only some parameters: camera (both seven-number gimbal and six-number eye/centre forms), viewall, projection ('o'/'p'), and full_render are explained with real syntax. But file, source, defines, imgsize, measure, colorscheme, and timeout_s get no mention at all, so roughly half the parameters remain undocumented outside a bare schema title.

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 a script to a file in the workspace') and immediately pins down the output format rule (taken from the file extension), listing the supported formats. It also explicitly differentiates itself from the sibling 'preview', so an agent can tell the two apart without opening either 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?

Gives an explicit when-to-use rule with the alternative named: 'Use render when the image is the artefact — a before and after pair, a figure for a page — and preview when you only want to look.' This is the clearest possible routing guidance and states the png case that selects this tool.

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