Modify elements

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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=true, so the safety profile is covered. The description adds real value beyond that: 'one undo step' (atomicity), 'Only the given fields change' (partial-patch semantics that support the idempotency claim), and a partial-success return shape '[{guid} | {error}]'. These are exactly the behaviors annotations cannot express.

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?

Three dense sentences, front-loaded with the core action, then input format, then return format. No filler; every clause carries information.

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 no output schema, the description covers the essential semantics: what changes, what doesn't, atomicity, and return shape. Minor gaps remain (undoName's role, how errors are keyed, whether nonexistent GUIDs fail the whole batch), but nothing critical for correct invocation 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 only 50% (undoName is undocumented, and the element item schema only describes guid while allowing arbitrary additionalProperties). The description compensates by explaining the patch object shape, that only listed fields change, and by enumerating concrete field names (height, thickness, begin, end, composite, layer, storyIndex, renovationStatus, elementId). This meaningfully exceeds what the schema conveys.

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 ('Changes fields') and resource ('existing elements'), plus the scoping detail that all changes land in one undo step. An agent can immediately distinguish this generic bulk-modifier from the type-specific siblings like modify_walls, modify_slabs, and modify_columns.

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 explains the input convention (field names mirror the type's create_* tool) which is genuinely useful, but it never states when to prefer this tool over the per-type modify_* siblings or set_property_values. Usage is implied rather than directed.

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