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

Annotations already declare non-readOnly, non-idempotent, non-destructive. The description adds one meaningful behavioral constraint beyond that: 'The map holds only new nodes,' telling the agent this call will not update existing nodes and that get_block must be consulted for shapes. It does not cover failure behavior, id generation, or whether the operation is atomic for multi-node payloads.

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?

Purpose and scope are front-loaded, and the node-shape and reference lines earn their space. The node-shape sentence is a dense fragment dump that costs some readability, but there is no filler.

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 mutation tool with a nested object payload and no output schema, the description supplies the payload structure, the attachment semantics, the parent default, and pointers to get_block and get_style_reference. It stops short of describing the response or id handling, but an agent has enough to invoke it correctly.

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 coverage is 100%, so the baseline is 3, but the description goes further by decoding the otherwise opaque `nodes` object (type.resolvedName, isCanvas, props, parent, nodes[], linkedNodes) and clarifying rootNodeId as 'the single top-level node in nodes to attach.' This is genuine added meaning over the schema's 'Flat map { nodeId: node }'.

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 and resource ('Build a section') plus the exact payload shape ('a flat map of new nodes plus the rootNodeId to attach under parentId'). The batch/section-building scope is clear, but it never contrasts itself with the sibling insert_node, so an agent must infer the boundary between the two node-creation tools.

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 default way to design a section for this business' gives clear positive context and the 'Contract: get_style_reference({ topic: "editing" })' line establishes a concrete prerequisite. No explicit when-not guidance or named alternative (e.g. insert_node for single nodes) is provided.

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