Add Sticker to CapCut Draft

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

Annotations already signal mutation (readOnlyHint=false) and open-world nature (openWorldHint=true). The description adds context that the sticker is placed on the timeline, requires an existing draft, and returns a JSON confirmation. It also discloses that extra_params allows passthrough of undocumented VectCutAPI fields, reinforcing the open-world behavior without contradicting annotations.

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 well-structured with a clear main sentence followed by Args and Returns sections. It is efficiently sized, though some parameter descriptions repeat schema information. The front-loaded purpose sentence earns its place, and overall the text is not bloated.

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 9-parameter complexity, rich schema, and annotations, the description provides necessary context: the target draft, timeline placement, and return type. It also directs to VectCutAPI docs for unmodeled fields. It lacks an explicit mention of how to obtain the sticker resource_id, but that may be covered by sibling tools or external assets, so completeness remains sufficient.

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 input schema covers all 9 parameters with descriptions, achieving 100% coverage. The description's Args section largely paraphrases the schema without adding new meaning, particularly for position/scale/rotation which are already documented. Extra_params is also described in the schema in greater detail than the tool description, so the description adds minimal value beyond what the schema provides.

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 'Place a sticker asset on an existing draft's timeline,' naming the specific verb, resource, and context. This distinguishes it from sibling tools like capcut_add_text or capcut_add_video by focusing on sticker assets and an existing draft timeline.

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 implies usage for adding stickers to an existing draft and mentions 'From capcut_create_draft' as a prerequisite. However, it does not explicitly state when to prefer this over sibling add_* tools or when not to use it, though the sticker-specific resource makes the intended use quite clear.

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