append_text_overlay

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

With no annotations, the description carries the full behavioral burden for what is clearly a write/mutation operation. 'Burn' hints at persistence, but nothing is said about reversibility, whether the overlay replaces or coexists with existing text, rendering implications, or permission requirements. Only the time-scoping behavior is disclosed.

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?

One front-loaded sentence with a useful parenthetical defining the time unit; nothing is wasted. It is arguably too terse for a 9-parameter mutation, but there is no filler or redundancy.

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, no output schema, and zero schema coverage needs considerably more: required-vs-optional semantics, defaults behavior, coordinate/alignment meaning, and side effects. The description covers only the temporal bounds.

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 description coverage is 0% across 9 parameters, so the description must compensate. It clarifies only that start_s/end_s are timeline seconds; project_name, color, bg_color, font_size, halign, and valign get no explanation, leaving the majority of the surface undocumented.

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 verb ('Burn') and resource ('a text title onto the timeline'), which is clearly distinct from clip-level siblings like add_clip or trim_clip. It stops short of naming how it differs from other overlay/effect tools, but the action is 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?

There is no guidance on when to choose this over siblings, no prerequisites (e.g., whether the project must already exist), and no note on what happens if the range overlaps existing overlays or exceeds the timeline length. Usage is left entirely to inference.

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