list_canvases

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

There are no annotations, so the description carries the full burden of conveying behavior. It states that the tool returns a collection of canvases and filters to active ones in the current session, implying a read-only operation without side effects. It could specify what metadata is included, but the core behavioral expectation is clear.

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 description is a single, front-loaded sentence that communicates the resource, scope, and result in minimal words. There is no filler or redundant phrasing.

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 zero-parameter list operation, the description is sufficient: it tells the agent what will be returned and under what conditions. No output schema exists, but the description makes the return value reasonably clear.

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?

The tool has zero parameters and the schema already reflects that with an empty properties object. Since there are no parameters to document, the baseline of 4 is appropriate; the description does not conflict with the schema.

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 uses a specific verb ('lists') plus a clear resource ('active canvases') and bounds the scope ('in the current session'). It is readily distinguishable from siblings like create_canvas, get_canvas_info, and delete_canvas, which perform different operations.

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 makes the operation's context explicit: it lists all active canvases in the current session. It does not explicitly mention when to choose this over get_canvas_info, but the broad list-vs-single distinction is clear enough for an agent.

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