Add Text to CapCut Draft

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

Annotations already indicate a write operation (readOnlyHint=false) and open-world behavior (openWorldHint=true). The description adds valuable behavioral context by explaining the return value (JSON confirming addition and used optional features) and clarifying that extra_params are merged into the request body. It does not contradict annotations, but could further disclose side effects or permission requirements; still, it goes beyond what annotations provide.

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 concise purpose sentence, a categorized bullet list of parameters, a return note, and an exclusion clause. Every section is relevant and easy to scan, with no redundant or wasted words.

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 (17 parameters, nested objects, no output schema), the description covers the return value, parameter usage, prerequisite (draft_id from capcut_create_draft), and the alternative for subtitles. This is sufficient for an agent to invoke the tool correctly in most scenarios.

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 baseline is 3. The description adds semantic grouping (basic styling, drop shadow, background panel) and explains extra_params as a passthrough for advanced VectCutAPI fields, enhancing the agent's understanding of how parameters relate. This goes beyond the schema alone, though not massively.

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 it adds a text element to an existing draft's timeline, with specific examples (title, caption, lower-third). It also distinguishes itself from the sibling subtitle tool via the 'Don't use when' clause, making its purpose unambiguous.

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 explicitly tells when NOT to use this tool (for burned-in subtitles from SRT) and directs the agent to capcut_add_subtitle instead. It also implies the prerequisite of an existing draft by referencing capcut_create_draft, which is clear contextual guidance.

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