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

Adds substantial context beyond the annotations: a null edit restores authored content, authored animation is preserved, unsupported changes refuse without rebuilding (no partial rebuild), operation_id and exact inputs must be preserved on retries, the call consumes the account's direct-edit allowance, and it is free. The quota and refuse-without-rebuilding details are exactly the kind of behavior annotations cannot express.

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 core action and supported fields, then proceeds to prerequisites, side effects, and cost in a logical order. Dense but nearly every sentence carries operational information; the terse 'Cost: Free: no credits.' phrasing is slightly awkward but not wasteful.

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 values need not be explained, and the description covers what remains: prerequisites, mutation and restore semantics, refusals, retry/idempotency discipline, quota consumption, and the follow-up download path. Nothing an agent needs in order to call this correctly 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 67%, and the description fills the most important gap the schema leaves: the meaning of a null `edit` (restores authored content), which the schema only types as null with no explanation. It also explains the provenance of base_version and output_id (from get_project_context) and the retry contract for operation_id. The `element` identifier format is only loosely implied by 'one returned editable canvas element'.

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 (change) on a specific resource (one returned editable canvas element) and enumerates exactly which fields are supported: text, color, hidden state. This cleanly separates it from siblings such as set_element_layout, set_scene_text, and adjust_style without needing to name them.

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 prerequisite chain (read get_project_context first, pass its base_version and output_id) and routes file delivery to a different tool (check_video with_download). It also states refusal behavior for unsupported changes. It stops short of explicitly contrasting with the nearest sibling, set_element_layout, so layout-vs-content selection is left implicit.

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