set_canvas_preset

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

With no annotations, the description carries the transparency burden. It discloses that the tool 'Writes the section size + pageSize object', which is a key behavioral effect. However, it does not mention whether the operation overwrites existing settings, requires specific permissions, or is reversible. The disclosure is partial but useful.

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 concise, front-loaded with the primary action, and includes only necessary details: the preset list and the custom requirement. Every sentence contributes to understanding the tool's functionality and parameter usage, with no wasted words.

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?

The description sufficiently covers the tool's core behavior for a mutation tool: what it sets (canvas preset), how to use custom dimensions, and what object it writes. Given the absence of an output schema, it does not need to explain return values. Minor omissions like mention of reportSessionId or page selection details are acceptable given the schema covers them, but the description could be slightly more thorough.

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 description adds value beyond the schema by enumerating the valid presets with their exact dimensions (e.g., '16:9 (1280x720)'), which is not fully captured in the schema's enum list. It also clarifies the relationship between 'preset=custom' and the width/height parameters. This supplements the 80% schema coverage effectively.

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 clearly states the tool's purpose: 'Set a page's canvas to a named PRESET'. It lists specific presets and dimensions, distinguishing it from sibling tools that handle other page or visual settings. The verb 'set' and the resource 'page's canvas' make the action and scope unambiguous.

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 provides usage context for the 'custom' preset by noting it 'needs width+height', but it does not explicitly state when to use this tool versus alternatives like set_page_display or resize_page. The guidance is implied from the preset list but lacks explicit exclusionary or alternative comparisons.

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