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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real context beyond them: it depends on host vision support, it compares against previous attempts, and it enumerates the four verdict categories returned. It does not state cost implications, URL accessibility requirements, or what happens when host vision is unavailable, which keeps it short of a 5.

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?

Four sentences with no filler, each carrying distinct information (trigger, inputs, output, capability dependency). It leads with usage conditions rather than a purpose statement, which is slightly less front-loaded but still immediately useful.

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?

The description does cover the return shape (timestamped evidence plus one of four recommendations) in lieu of an output schema, which is the right call. But for an 11-parameter tool with nested objects and zero schema documentation, leaving every parameter unexplained is a substantial completeness gap an agent must close by guessing.

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 0% across 11 parameters including nested objects (requirements, previousAttempts, retryPrice, editableAssets), yet the description explains none of them. Worse, it says it compares 'an existing fal result URL or a local intake clip' while the schema requires falVideoUrl and exposes no local-clip parameter, creating ambiguity about the actual input contract.

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 ('Review a generated video' / 'Compare ... with the brief and previous attempts') and says what comes back (timestamped evidence plus a recommendation). It does not name or distinguish the sibling decide_render_retry, and the 'whether to rerender' framing overlaps that sibling's apparent territory, so the boundary is left fuzzy.

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 three concrete triggers: the video missed its brief, a defect keeps repeating, or the user asks about rerendering. That is clear when-to-use context, but there is no when-not guidance and no explicit pointer to decide_render_retry as the alternative, which matters given the near-identical decision framing.

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