flow_generate_video

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

With no annotations provided, the description must carry the full behavioral burden, and it does: it discloses credit costs per model, submit-only async behavior, the mediaId handle return, polling requirements, off-grid duration snapping, aspect ratio constraints, and structured error behavior for invalid inputs. This is unusually transparent.

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 information-dense, with the most critical warning (credit cost) front-loaded in red. Each sentence serves a purpose: mode list, submit-only behavior, model key syntax, next steps, multilingual triggers. The structure is logical, though the sheer density might overwhelm some agents; still, it earns its length.

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 tool with no output schema, the description covers all necessary context: every mode, parameter interactions, credit implications, async flow, polling, language triggers, and even the live catalog via flow_status. It leaves no obvious gap in what an agent needs to invoke it correctly.

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 adds value beyond the schema by explaining the model key semantics (mnemonic+durationSeconds, credit tiers), the exact usage of videoMediaId for each mode, and mutual exclusivity rules (image vs keyframes vs videoMediaId). It does not repeat schema descriptions but complements them with operational context.

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 states an explicit verb+resource ('Submit an AI video generation to Google Flow') and distinguishes it from siblings by detailing the video-specific modes (t2v/i2v/r2v/interpolation/extension/upsampler/edit) and the explicit-only routing rule. It clearly differentiates from flow_generate_image and flow_status.

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?

Provides explicit when-to-use ('USE ONLY when the user explicitly asks for Flow / Veo / abra video') and when-not-to-use via the config note. It also tells the agent the exact follow-up sequence (poll with flow_status, re-call with download=true) and lists alternative tools implicitly by covering all video generation paths.

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