set_animation

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

Annotations cover safety (readOnly=false, destructive=false, idempotent=true), and the description adds the critical lifecycle facts annotations cannot convey: changes are live-only, lost on reload, tracked in pending_changes, and undoable via revert_changes. That is exactly the extra behavioral context a mutation tool needs.

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?

Two sentences, zero filler, and the most consequential fact (live preview, not saved) is front-loaded before the parameter summary. Every clause carries information.

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 9-parameter tool with no output schema, it covers the ephemeral-preview model, the persistence path, and the undo path, which is the essential missing context. Minor gaps remain: no guidance on whether play/stop/pause combine, and mixerIndex/actionTimeScale semantics are left to the schema.

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 only 56%, so the description compensates by splitting the parameters into two semantic groups — mixer-level (timeScale/time) and action-level (play/stop/pause/weight by clip name) — which clarifies intent beyond the raw schema. It still leaves mixerIndex and actionTimeScale unexplained, keeping it below a 5.

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+resource: it controls animation playback via the mixer and actions, with the '[LIVE PREVIEW]' tag scoping it to the running scene. It never names sibling animation_details as the read-only counterpart, so the boundary is implied rather than explicit, but the purpose itself is unambiguous.

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 gives strong context for when the effect applies: browser-only, not persisted to source, recorded in pending_changes and reversible with revert_changes. It stops short of explicitly stating when to reach for this versus animation_details or pending_changes, so it's clear context without named alternatives.

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