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

Annotations already declare a non-read-only, idempotent, non-destructive, closed-world operation. The description adds valuable behavior beyond that: it returns a public link, plays and downloads as video, enforces a 24–360 bar past window, and instructs the agent to present the film as a replay, never a forecast. It does not discuss permissions or rate limits, but the added context is substantial.

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 front-loaded with the main action and then adds constraints and output details. It is dense but every sentence carries information: what is created, what is included, what is returned, limits, and the presentation rule. It could be split into shorter sentences for readability, but it is not bloated.

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 14-parameter mutation tool with no output schema, the description covers the essential output (public link, playback, download), the content options, and hard constraints on the time window. It also includes a critical presentation rule about not framing the film as a forecast. It does not address edge cases such as invalid windows or visibility/permissions, leaving a small gap.

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 meaningful constraints not fully captured by the schema: the window must be in the past and contain 24–360 bars, which directly qualifies the from and to parameters. It reinforces the optional content for drawings, marks, structure, and machine, but does not explain title, kicker, headline, palette, or seconds beyond the schema.

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 a specific verb and resource: 'Seal a past window of the tape into a FILM.' It makes clear that the tool produces a replay video with drawings, optional structure, and machine trades. It does not explicitly distinguish this from siblings like replay_open or chart_image, so sibling differentiation is absent.

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?

The description implies when to use it by giving constraints: '24 to 360 bars; the window must be in the past.' However, it never names alternatives or says when not to use this tool instead of replay_open, chart_image, or replay_record. The usage context is present but not explicit.

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