Play Song

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

With no annotations, the description carries the full burden; it does disclose the lookup order and fallback path, which is real behavioral context. It omits side effects an agent needs: whether calling it interrupts current playback, what happens if no device is active, and what occurs when nothing matches in the catalog.

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 first sentence states the action and lookup order, followed by a short trigger paragraph. Slight redundancy between the title line and the second paragraph, but nothing extraneous.

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?

Output schema exists, so return values need no explanation, and the search-then-play mechanic is covered. For a playback-mutating tool with zero annotations, it should still say whether playback starts immediately, what device state is required, and how failures are signaled.

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%, so query, index, and device are already documented in the schema. The description only echoes 'by name' (title/artist), adding no disambiguation for index selection or device behavior beyond the schema text. Baseline 3 applies.

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 and resource ("Play a song by name") and adds the distinguishing mechanic: Liked Songs first, then catalog fallback. That mechanic separates it from play_liked_song and play_track, but the siblings are never named, leaving the agent to infer the contrast.

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?

Explicit trigger condition: "This is the tool to use when the user says 'play <something>'." It gives a clear when-to-use but no exclusions, e.g. when to prefer play_track with a known ID or play_liked_song directly.

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