new_element

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

Annotations only declare readOnlyHint=true; the description adds real behavioral context beyond that — the node is structurally valid, comes from the 'real' (non-mock) factory, is returned unpersisted, and must be edited and then placed into a section's children. It doesn't cover failure modes or the returned node's shape, keeping it from 5.

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?

Two tight sentences, front-loaded with the core action and return value, then the follow-up step. No filler; slightly compressed phrasing ('real builder factory') costs a bit of clarity.

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 2-param factory tool with no output schema, the description could say more about the returned node's structure (beyond naming specials/style) or how it relates to sibling builders. The schema covers inputs and it points at list_elements for types, so it is adequate but not fully self-contained.

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% with rich descriptions for both `opts` and `type`, so the schema already does the heavy lifting. The description adds no parameter detail beyond the workflow hint, so the baseline 3 applies.

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?

Specific verb+resource: 'Build a single structurally-valid element node from the real builder factory.' Clear what it produces and distinguishes from siblings like new_section/new_row by scoping to a single element. It doesn't explicitly contrast itself with those siblings, so it stops short of 5.

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?

It implies a workflow ('edit its specials/style, then place it in a section's children'), which tells the agent what to do after calling it. However it never states when to prefer this over alternatives (new_section, add_section, new_page_skeleton) or what prerequisites exist, so usage is only implied.

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