video_validate_text_layout

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

With no annotations, the description must carry the full behavioral burden; it does disclose the checks performed and that output is a warnings list plus a clean boolean. It never says whether the tool is purely analytical or may write files, which matters because the schema exposes an `overwrite` parameter described as "allow replacing existing media" — an agent cannot tell whether this tool mutates anything. Warning severity levels are also undisclosed.

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?

Front-loaded with purpose and check list, then structured Args/Returns sections — each line carries information. The Args block slightly over-indents across lines and the Returns line is redundant given the output schema, costing a little economy.

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?

For a validation tool with a loose schema, the overlay contract is well covered and the output shape need not be restated since an output schema exists. Gaps remain: the `overwrite` parameter's purpose, whether any side effects occur, and how warnings are ordered or prioritized relative to the `clean` flag.

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 only 20%, but the description compensates strongly by enumerating the overlay spec keys (text, position, size, color, shadow, start_time, duration), which the schema leaves as an untyped `additionalProperties: true` object, and by explaining what video_width/height and background_color are used for. It omits the `overwrite` parameter entirely, leaving one of five parameters unexplained.

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?

States a specific verb and resource ("Validate a set of text overlays") and enumerates exactly what is checked: overlap, contrast, safe positioning, overlay density, missing shadows. It is clearly distinguishable from sibling mutators like video_add_text or video_add_texts, though it never names them explicitly.

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 phrase "before rendering" gives a clear workflow slot for when to call it. It does not, however, state exclusions or point at the alternative (e.g., call video_add_text to apply overlays after validation passes, or video_preflight/quality_check for whole-video checks), so routing is inferred rather than explicit.

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