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

Adds real context beyond annotations: saves a playable project, unsupported changes refuse without rebuilding, retries must reuse operation_id and exact inputs, consumes the account's direct-edit allowance, and is free of credits. It doesn't spell out what state is overwritten or what the destructive mutation affects, which would complete the picture for a destructiveHint=true tool.

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 and dense with useful facts; most clauses earn their place. The semicolon-chained phrasing and 'Cost: Free: no credits' are slightly awkward, but nothing is padding.

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?

Given an output schema exists, return values needn't be described. For a destructive, versioned mutation it covers prerequisites, failure mode, retry behavior, and billing. It leaves the direct-edit allowance's limits and the precise 'unsupported changes' condition implicit.

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%, so the baseline is 3. The description still adds value by naming the source of the scene shape (get_project_context), specifying which output_id and base_version to pass, and reinforcing retry semantics for operation_id.

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+resource ('Insert one scene') and a concrete placement rule ('after null inserts it at the start'), which separates it from move_scene, remove_scene, and replace_scene_screen. An agent can identify the operation 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?

Explicit prerequisites: 'Read get_project_context first and pass its base_version and selected output_id', and it routes file generation to 'check_video with_download'. It doesn't explicitly say when to prefer siblings like replace_scene_screen or how it differs from move_scene, but the workflow context is strong.

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