set_fog

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

Annotations only declare safety semantics (readOnlyHint=false, idempotent, non-destructive); the description adds the crucial behavioral facts: the change is browser-only, never persisted to source, lost on reload, tracked in pending_changes, and reversible via revert_changes. That is well beyond what the annotations disclose.

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 with zero filler, and the highest-risk constraint ([LIVE PREVIEW], not saved) is front-loaded before the functional description. Every clause carries non-redundant 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 non-destructive preview mutation with full annotation coverage and a complete parameter schema, the description supplies everything the agent needs: persistence semantics, undo mechanism, and which scene properties are affected. No output schema exists, so no return-value description is required.

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 100%, so the baseline is 3. The description groups the parameters ('color, near/far or density' and background color), reinforcing the schema but adding no new syntax, constraints, or defaults beyond what is already documented per-property.

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 (Change) plus resource and scope: scene fog (color, near/far or density) and the background color. This distinguishes it from read-only siblings such as fog_details and scene_background, so an agent can route correctly without opening the 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?

Explicitly frames when this applies — live preview only, not written to source, lost on reload — and names the follow-up path (pending_changes → code edits) plus the undo path (revert_changes). It gives clear operating context but no explicit 'use X instead when you want persistence' alternative tool.

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