Upscale an Existing Google Flow Video Job

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

Annotations already declare destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is partly covered. The description adds genuinely new context beyond the annotations: it may consume credits, requires explicit authorization, and rejects unavailable/upgrade-only options rather than silently downgrading.

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 short, front-loaded sentences with no filler; the exclusivity claim, the guardrail, and the cost warning each carry distinct information. Minor slack in adjectives like 'real' that don't add selection 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 a mutation tool with a 100%-covered schema and no output schema, it covers the key agent-facing risks: credit consumption, authorization, exclusivity, and rejection of bad options. It stops short of describing the return/polling flow (though timeout behavior is noted in the schema), which would fully close the loop.

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 the schema already documents jobId, factor, timeoutSeconds and confirmCreditSpend in detail. The description adds no parameter-level syntax or format guidance (e.g. where factor values come from is only stated in the schema, not the description), so baseline 3 applies.

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 ('Flow video upscaling') and frames itself as 'the exclusive path,' which separates it from flow_generate_video and similar siblings. It does not name any sibling explicitly, so differentiation is achieved via the exclusivity claim rather than routing language.

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 a clear negative guidance rule ('Never right-click or control Flow with generic browser/computer-use tools') and a precondition (explicit authorization for credit spend). It implies the alternative path (this tool vs. generic automation) but never names a specific sibling tool to use instead in edge cases.

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