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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the mutation profile is covered. The description adds nothing beyond that: it does not say whether advancing past the last frame wraps, clamps, or errors, nor whether playback state changes. For a non-idempotent state-changing tool, that boundary behavior is exactly what is missing.

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 single short phrase is front-loaded and free of padding. However, at three words it tips into under-specification rather than economy, since no constraint or context sentence shares the space.

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?

An output schema exists, so return values need not be described, and the zero-parameter schema needs no explanation. What remains uncovered is the operational context: required object/movie state and end-of-range behavior, both of which an agent needs to invoke this 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?

The tool takes zero parameters, so there is nothing for the description to elaborate and the baseline applies. The empty schema means no parameter ambiguity exists.

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?

"Advances one frame" gives a specific verb (advances) and resource (frame) that an agent can act on, and it is distinguishable from the inverse sibling "backward" and from "frame", which sets a specific frame. It stops short of naming any sibling explicitly, so the differentiation is inferential 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?

There is no when-to-use guidance at all: nothing says whether this requires a loaded multi-state object or an active movie, nor when to prefer it over "frame", "mplay", or "backward". The agent is left to guess the preconditions entirely.

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