Generate a video with Veo

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

With no annotations, the description carries the behavioral burden and does it well: it discloses the cost model (per second), latency (1-5 minutes), and the filesystem side effect plus return value ('saves an MP4 to disk and returns its path'). It omits other traits an agent might want, such as whether output is deterministic given a seed or whether partial failures leave files behind.

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?

Three sentences, no filler. The capability and its input modes come first, then the cost/latency caution, then the output side effect — front-loaded in descending order of decision value.

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 an 11-parameter generation tool with no annotations and no output schema, the description covers the essentials an agent needs to decide and call correctly: what it produces, what it costs, how long it takes, and what it returns. Remaining gaps (auth/permission needs, idempotency, failure behavior) are secondary for this tool type.

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 91%, so nearly every parameter is already documented in the schema, including the image/first-frame and lastFrame/requires-image relationship. The description's 'optionally starting from an image ... and ending on another one' restates the schema rather than adding new meaning. Baseline 3 is correct when the schema does the heavy lifting.

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 ('Generate a video from a text prompt with Google Veo') and enumerates the two input modes (text-to-video, image-to-video with an optional last frame). An agent knows exactly what capability this exposes. It does not name the sibling list_models, which is referenced only in the schema, so sibling differentiation is implied rather than stated.

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 concrete operational context: paid per second of video, 1-5 minute latency, and an explicit instruction to 'ask before generating several variants'. That is real when-to-be-careful guidance. It stops short of naming alternatives or a when-not-to-use condition (e.g. reusing an existing file), so it is clear context rather than full routing guidance.

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