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

No annotations are provided, so the description carries the full burden and handles it thoroughly. It discloses asynchronous behavior (returns 202 with a job id, poll getApiJob until success), billing details (per-second, charged only on success, 0.2 credits per second), rate limits (50 concurrent jobs, 429 PENDING_JOBS_LIMIT), and auth requirements (API key, user scope). It also clarifies what the result contains and how to read it.

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 description is long but every sentence earns its place: constraints, billing, async flow, rate limits, credits, and related tools. It front-loads the core action and then layers essential operational details in a logical order without redundancy.

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?

With no output schema and no annotations, the description covers all necessary operational aspects: request constraints, async response handling, polling instructions (getApiJob with wait: 30), result extraction, billing, rate limits, and prerequisites. An agent has enough information to invoke the tool correctly and handle the outcome.

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 100%, so both video and request_id are already documented in the schema. The tool description adds operational context—like the source endpoints and how to locate results—but does not add significant new meaning beyond what the schema already states. Baseline 3 is appropriate.

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 opens with a specific verb and resource: 'Upscale a previously generated video to twice its resolution (2x).' It distinguishes itself from siblings by naming createVideo and editVideo and their respective purposes, so an agent can immediately identify what this tool does and how it differs.

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 provides explicit when-to-use context: pass a video URL received from createVideo, createVideoFromReferences, or editVideo; only videos under 960x960 and generated within 7 days are accepted. It also states when-not-to-use conditions (external videos not accepted, larger sources rejected) and names related tools and their specific uses, giving the agent clear routing guidance.

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