Add a text overlay to a CapCut draft using a template with a text layer. Specify text, position, color, duration, and timing.
Add a text overlay. Requires a text template (a draft with a text layer; see CAPCUT_TEMPLATE_DRAFT).
| Name | Required | Description | Default |
|---|---|---|---|
| posX | No | ||
| posY | No | ||
| text | Yes | ||
| atSec | No | omit to append right after the last text on the target track | |
| color | No | hex e.g. #ffffff | |
| draft | Yes | ||
| durSec | No | ||
| fontSize | No | ||
| trackIndex | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
There are no annotations, so the description must disclose behavioral traits. It does reveal one hidden requirement (the draft must already contain a text layer), but it does not say whether this mutates the draft, whether saving is required afterward, or what side effects occur on existing timeline data. For a mutation tool this is a substantial transparency gap.
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 a single tight sentence with no filler; the core purpose is front-loaded and the prerequisite is placed immediately after. The reference to CAPCUT_TEMPLATE_DRAFT is terse but not wasteful, though it is unclear what that symbol points to.
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?
A 9-parameter mutation tool with no annotations and no output schema cannot be adequately described in one sentence. The description omits semantics for the majority of parameters, return behavior, and side effects, leaving an agent with substantial ambiguity.
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?
With only 22% schema description coverage, the description needed to explain most of the 9 parameters, but it only helps define 'draft' as a text template. Parameters such as posX, posY, durSec, fontSize, and trackIndex remain undocumented in both schema and description.
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 opens with a specific action and object: 'Add a text overlay,' which clearly identifies what the tool does. The template requirement adds useful context, but it does not explicitly contrast the tool with sibling add_* tools such as add_sticker or add_video, so differentiation relies mostly on the tool name.
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 only usage guidance is the prerequisite that a text template draft is needed and the pointer to CAPCUT_TEMPLATE_DRAFT. It gives no guidance about when to choose this tool over the many sibling add_* tools, and it notes no exclusion criteria.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.