Modify roofs

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

Annotations declare destructive/idempotent/not-readonly, and the description goes well beyond them: partial-update semantics, per-item type validation with 'other items still run' error isolation, return shape [{guid} | {error}] in input order, and a single undo step. This is exactly the behavioral context an agent needs for a batch mutation.

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?

Single dense paragraph, purpose front-loaded in the first clause, no filler sentences. It is long, but proportionate to an enormous schema and a class-scoped tool; the density is justified rather than padded.

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 very complex mutation tool with 100% schema coverage and no output schema, the description covers class-specific fields, patch semantics, validation behavior, error/return handling, and undo scoping. Nothing an agent needs to call it correctly is missing.

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 schema already documents every field. The description still adds non-derivable meaning: which fields belong to which roof class, that edge indices refer to the stored pivot polygon 'as returned by get_element_details', and that field syntax matches create_roofs.

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+resource ('Changes existing roofs') and immediately distinguishes behavior by class (SinglePlane vs MultiPlane fields), plus names the create_roofs sibling as the field reference. An agent can tell this apart from create_roofs and modify_elements without opening a schema.

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?

Clearly conveys patch semantics ('Only the given fields change; the others keep their values') and preconditions ('Each item must be an element of this type'). It does not explicitly say when to prefer this over create_roofs or the generic modify_elements, but the context is clear enough to select the tool.

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