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

Annotations only declare readOnlyHint=false and destructiveHint=false; the description goes further by stating the call is free, that nothing is planned/voiced/rendered at creation time, and that a render quote (render_cents) comes back, which is real cost/state context an agent needs before calling. It stops short of saying what happens on repeat calls or limits on project count.

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 the key facts (free, nothing rendered), then a compact Args block and a Returns block. Every sentence carries information an agent cannot get from the schema, and the Args/Returns structure makes scanning trivial.

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 6-parameter creation tool with a nested settings object and no output schema, the description covers cost, side effects, parameter meanings, field constraints, and the return shape including the quote object. Nothing essential to invoking or interpreting the call 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 description coverage is 0%, and the description compensates fully by documenting all six parameters: script with its 10,000-character cap, optional title, aspect with the 9:16 default and enumerated alternatives, visual_style as a look id from studio_enums, settings as a partial object (voice, captions, music), and origin's "create" value. That is meaning well beyond the bare JSON schema.

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 ("Start a Video Studio project from a script") and immediately bounds the effect with "nothing is planned, voiced or rendered," so an agent knows exactly what state the project lands in. It also names the follow-on tools (studio_plan, studio_get_project), which separates it from downstream studio operations.

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?

Gives an explicit lifecycle order ("Next: studio_plan, then studio_get_project") and points at studio_enums for valid look ids and settings keys. It does not distinguish itself from the sibling studio_create_from_audio, so an agent with an audio file still has to infer which creation entry point applies.

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