Speed Change

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

Goes well beyond annotations: it discloses that the operation always fails before mutation, why (no setter in ExtendScript/UXP), and that the QE fallback was intentionally not used. This is exactly the kind of context needed for a non-functional stub.

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 tight sentences, front-loaded with the unavailability verdict, then the reason, then the redirect. No filler.

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 and the safety profile is covered by annotations; for a deliberately failing tool, the description supplies everything an agent needs to understand and avoid it.

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%, with node_id, speed_percent and reverse all documented in the schema, so the description is not required to carry parameter meaning. It adds nothing further, which is the baseline-3 case.

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 precisely what the tool does — nothing, because it fails before mutation — and explains the API reason (no documented setter; QE setSpeed deliberately avoided). This unambiguously distinguishes it from set_clip_speed_qe and get_clip_speed.

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?

It explicitly names the alternative, set_clip_duration, and the condition that selects it ('to change how long a clip runs'). An agent will never waste a call here by mistake.

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