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

Goes well beyond the annotations by disclosing cost/side-effect scope ('Layout and creation never run media generation or charge coins'), the deterministic frame placement algorithm (near-square ceil(sqrt(N)) grid, row-major, no overlaps), and the retry contract ('Use the SAME request_id when retrying'). These are behaviors an agent cannot infer from readOnlyHint=false / idempotentHint=true alone.

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 trigger, which is good, but the single dense paragraph chains layout algorithm, cost policy, cross-tool routing, and reference guidance together. Each sentence is relevant, yet the grid-placement detail competes for attention with the far more critical fact that operations structure is undocumented.

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?

Strong on routing, cost, and retry behavior, and no output schema exists so return-format explanation is not owed. However, for a mutation tool whose only real payload is a 1-200 item operations array, leaving that parameter entirely unexplained is a material hole an agent will hit on first invocation.

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% for all three parameters, so the description must compensate and largely does not. Only request_id gets meaningful treatment (retry semantics); 'operations' — an opaque array of up to 200 objects that defines the whole draft — is described only as 'semantic operations' with no shape, allowed operation kinds, or ordering rules, and 'name' is unexplained.

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: 'Creates a native Canvas draft from semantic operations', and names the trigger scenario (new Canvas project, moodboard, storyboard). It partially differentiates from siblings by pointing to layout_composition for storyboard/pipeline/branching work, but mentioning storyboard here while a sibling aimixer_canvas_create_storyboard exists creates ambiguity about which tool truly owns that case.

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?

Explicit trigger ('Use when the user asks to create a new Canvas project'), explicit alternative with ordering ('use the shared layout_composition operation AFTER adding/configuring draft nodes and exact connections'), and prerequisites ('Read capabilities first'). It also gives a judgment rule: use direct references unless a character/location sheet is needed, and do not invent paid stages.

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