art.canvas.create

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

With no annotations present, the description carries full responsibility for explaining side effects. It only says 'create' a 'session', giving a minimal behavioral fact, but does not disclose what happens upon session creation, whether a previous session is replaced, whether the operation persists or is ephemeral, what the return value is, or any permissions or resource requirements.

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?

The definition is a single clear sentence, with the main verb and resource immediately accessible and no filler words. It is concise and appropriately sized for a simple creation operation, though sparse.

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?

There is no output schema and no annotations, so the description needs to explain the overall usage context and effects. It merely states that a session is created, but does not mention what the agent receives in return, what the session_id is used for, or how it relates to subsequent drawing operations. The tool cannot be confidently and safely invoked based on this description 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 100%, so each parameter (width, height, asset_id, bg_color, session_id) already has documented meaning. The description adds no extra parameter context beyond the overall purpose of creating a drawing session. This meets the baseline of relying on the schema's parameter descriptions, but no more.

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?

The description states a specific verb ('Create'), a distinct resource ('new pixel canvas session'), and is clearly separated from the many sibling canvas operations like set_pixel, draw_rect, get_state, and save by naming the session itself. This is the only kind of session creation tool among the siblings, so an agent can reliably identify what it does.

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 description offers no guidance on when to use this tool versus the many drawing and state-reading canvas tools, or when a new session is needed instead of reusing an existing one. There is no mention of sequencing, prerequisites, or alternatives, so the agent must infer the usage context.

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