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

Goes well beyond the annotations: it discloses credit spend, that inputs are sent to the configured model provider, that optional settings overwrite the saved project, that repeats reuse running/completed jobs while a failed job starts a new paid attempt, and that sign-in is required for the Abracadabrax account. These are exactly the cost, auth, and side-effect facts an agent needs and cannot get from the schema.

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?

A single dense block, but front-loaded with the critical constraint (never generate on your own initiative) before routing, cost, and return-value details. Each sentence carries distinct information; it is long because the behavioral surface is large rather than padded, though the negative-workflow list could be tightened.

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?

Covers the full decision surface for a 7-parameter, open-world-false mutation: cost, auth, idempotency-like reuse behavior, job-id return and polling path, and explicit exclusion of adjacent workflows. With an output schema present, no further return-value detail is required.

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 43%, and the description compensates partially by explaining that the optional settings overwrite the saved project (which frames tab, ratio, duration, model_id as overrides). However, it adds no per-parameter meaning for ratio, duration, or model selection beyond what the schema fragments already say, leaving the coverage gap only partly closed.

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 ("Start the generation for a prepared project") and clearly frames it as the execution step that follows prepare_media_project. The text also delineates what it is not (media-to-media workflows), so an agent can separate it from get_media_job and update_media_project without inspecting schemas.

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 when-to-call (only after the user explicitly asked to generate, never on own initiative), the follow-up step (poll get_media_job), and negative routing (not for uploaded/reference images, editing, background removal, upscaling, try-on, image-to-video). Both alternatives and exclusions are named.

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