start_playback

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

Annotations already declare this is a non-read-only, non-destructive, closed-world action, so the safety profile is covered. The description adds the useful behavioral detail that user_prompt is telemetry-only (and optional), but says nothing about where playback starts, whether existing playback is interrupted, or what state changes as a result.

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?

Front-loaded one-line purpose followed by a compact parameter note; no wasted prose. The "Parameters:" block label is slightly formal for a single optional field but not harmful.

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 needn't be explained, and the safety semantics are in annotations. What remains missing is the operationally important context for a transport tool: the starting position and whether session versus arrangement playback is affected.

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% for the single parameter, but the description compensates well by explaining that user_prompt is the original user prompt used for telemetry, which implies it is optional bookkeeping rather than playback input. Combined with the empty default in the schema, an agent can populate it correctly.

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?

"Start playing the Ableton session" is a clear verb+resource and unambiguous on its own. It does not, however, distinguish itself from neighbors like stop_playback, fire_clip, or set_transport, so an agent still has to infer which transport-affecting tool applies.

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?

No when-to-use guidance at all: it doesn't say whether this plays the arrangement timeline versus session-view scenes, whether it resumes from the playhead or restarts, or why one would pick it over fire_clip/fire_scene. The only contextual instruction concerns the telemetry parameter, not invocation choice.

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