Tweak one existing element (merge changed fields)

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

The description discloses important behavioral traits: merge semantics (only provided keys change), null to remove a key, id can target any element anywhere in the tree (including nested in groups or masks), and the result is re-validated before acceptance. The annotations provide basic readOnly/destructive hints, but the description adds crucial operational detail without contradicting them.

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 four sentences with no unnecessary words. It front-loads the core action and then efficiently covers scope, removal semantics, an alternative usage, and validation, with every sentence earning its place.

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?

Given the tool's complexity (3 params, nested object, output schema exists), the description is fully complete. It covers purpose, scope, parameter behavior, alternative tools, and validation, while the output schema handles return value details.

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 significantly enriches parameter understanding beyond the schema. It explains that patch replaces whole nested values (e.g., keyframe_animations) and that null removes keys, and it clarifies that id can be any element anywhere in the tree. Even though schema coverage is 100%, the description adds critical usage nuances and an example.

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 changes fields on an existing element by merging in a partial element, making it distinct from add_element, delete_element, and set_project. The title 'Tweak one existing element (merge changed fields)' reinforces this specific purpose.

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 explicitly states this is for tweaking an existing composition and directs to set_project for creating a composition or changing many elements at once, providing clear when-to-use guidance and an alternative. The context of editing an existing element vs. creating/deleting is also implied.

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