add_text_overlay

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

The description discloses the core behavior (burning text onto every frame) and the underlying filter. However, with no annotations, it doesn't explain that the tool creates a new output file rather than modifying the original, nor does it mention preservation of audio or any side effects. This leaves the agent to infer behavior, but the description is not misleading.

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, focused sentence that front-loads the core purpose and implementation detail. No unnecessary words or repetition.

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?

The description is adequate for a video tool with high schema coverage. It lacks explicit mention of return values or output behavior, but for a relatively simple operation, the missing information is minor. The context signals (siblings, no output schema) make this short description acceptable.

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%—all 7 parameters have descriptions. The tool description adds context about the drawtext filter, but doesn't provide additional semantics beyond what the schema already offers. Baseline 3 is appropriate.

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 states a specific action ('Burn a text string') and resource ('onto every frame of a video'), using a known technique ('ffmpeg drawtext filter'). This distinguishes it from siblings like burn_subtitles, which handle subtitle files rather than arbitrary text.

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 clearly implies the use case: adding a static text overlay to a video. It doesn't explicitly mention when not to use it or compare with alternatives, but the context is clear enough for most agents.

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