list_media_players

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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds only that results are limited to 'active' players, which is useful filtering context, but says nothing about whether an empty list is possible or what identifying fields each player carries.

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?

A single six-word sentence with the scope qualifier front-loaded. There is no filler and nothing to trim.

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?

With no output schema, the description is the only place an agent can learn what a returned player looks like (name, bus ID, playback state) or whether the call can return an empty list. For a zero-param enumeration tool that gap is the main remaining deficiency, but the core contract is still intelligible.

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 no parameter semantics for the description to compensate for. Baseline 4 applies; nothing is missing on this dimension.

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 ('List') and resource ('MPRIS2 media players') with a scope qualifier ('all active'). An agent knows exactly what it enumerates, though it never names or contrasts itself with the related siblings get_media_status, media_play_pause, or media_next.

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?

Usage is only implied: 'list all active' suggests a discovery use case, e.g. before targeting a specific player. It never says when to prefer this over get_media_status, which returns playback state and is the closest sibling, so the agent must infer the distinction.

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