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

With no annotations at all, the description carries the full behavioral burden and does well: it discloses per-started-minute billing at €0.02, the Authorization: Bearer auth requirement, the output format (signed link), and the framing behavior (scale to fit, blurred fill, no cropping). It omits limits an agent might care about, such as input size caps, failure modes, or link expiry.

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 prose is front-loaded with what the tool does and how it looks, then billing, then a compact parameter list; almost every clause carries information. The trailing parameter block reads as a run-on and repeats the parameter names, but that repetition is what makes the zero-coverage schema usable.

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?

An output schema exists, so return-value explanation is not needed, and the description instead covers the operational facts an agent needs: cost model, auth header, output medium, and all parameter semantics. Nothing essential for correct invocation is missing.

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 0% and every parameter is undocumented in the schema, so the description must compensate — and it does, listing all seven parameters with units (seconds), accepted values and defaults (aspect 9:16, font_size 30), and the range 12-72. It even clarifies that segment timestamps are in the original video's timeline, which the schema does not convey.

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 and resource ('Cuts start-end from a video and reframes') plus the concrete output (MP4 with burned-in captions) and the exact aspect ratios supported. An agent can distinguish this from a generic clip or subtitle tool without opening the schema.

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?

It clarifies the internal fork between supplying 'segments' and using 'auto=true', which is genuine usage guidance. It never addresses when to choose this over siblings like video_clip, subtitles, caption or highlight_clip_finder, so external routing is left to inference.

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