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

Beyond the readOnly=false/destructive=false annotations it discloses credit cost with a free pricing probe, that the run is asynchronous and returns welt_id, wall-clock expectations ('about a minute' vs '5-15 min'), a post-run studio workflow, and a real limitation ('flying through walls does not'). That is the mutation/async/cost profile an agent needs.

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-loads what it builds and the cost caveat, then moves to inputs, then async behavior and limits. Dense with parenthetical asides and some overlap with schema text, but nearly every sentence carries actionable information.

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 costly, asynchronous, multi-input generation tool with no output schema, the description covers cost, duration, return handle, polling target, downstream use of results, and a geometric limitation — nothing needed to call it correctly is missing.

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 coverage is 100%, so the baseline is 3; the description adds value by explaining the entwurf-vs-voll trade-off in time terms and by spelling out the two mutually exclusive input paths (loc_id+variante vs quell_bild_id) at the tool level rather than per-field.

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 artifact ('Build a walkable 3D WORLD (Gaussian splat, World Labs Marble)') plus the exact input ('from ONE location picture'), which differentiates it from siblings like lab_generate_location_variants or lab_depth_map that also consume location imagery.

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 concrete selection rules: a board time variant (loc_id + variante) OR a project gallery image (quell_bild_id), plus 'call get_cost: true first' and 'poll lab_welt_status'. It stops short of stating when NOT to use it versus neighbouring world/location tools, so it is strong context but not a full when/when-not map.

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