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

Annotations already declare the full safety profile (not readOnly, idempotent, destructive, openWorld), so the bar is lower. The description adds a useful behavioral nuance — that looping holds the current track rather than 'cutting to a different track' — but it never explains what the destructiveHint entails, e.g. whether the previous loop state is lost or what happens on 'off'.

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 short, front-loaded sentences with zero filler. The core action is stated first and the rationale second, so an agent gets the essential meaning immediately.

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 both parameters are fully covered by the schema. The description supplies purpose plus a concrete use case, leaving only the interaction with sibling stream controls unaddressed.

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 both 'loop' and 'seconds' fully documented in the schema, so the baseline is 3. The description adds no syntax or format detail beyond what the schema already provides.

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?

States a specific verb+resource ('Make the running stream loop a section, or stop looping') and covers both the on and off states. An agent can tell this controls stream looping, but the description never distinguishes it from the closely related siblings set_stream_intensity, start_stream, and restart_stream.

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 second sentence supplies a usage context (holding a mood over a menu screen, pause, or interstitial), which implies when this tool is appropriate. However, there is no explicit 'when not' and no routing to alternatives such as set_stream_intensity or start_stream, leaving the agent to infer the distinction.

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