Search tracks with full compound filtering

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

With readOnlyHint=true, the safety profile is already known. The description adds valuable behavioral context: the whole-library scope, that every filter composes, and the critical distinction that 'vibes' only matches ~3,800 curated tracks while mood fields cover all 9,000+. It also explains the mood_vibes prediction logic. This goes beyond the annotation.

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?

The description is dense but efficient. Two well-structured sentences cover the full scope and a crucial usage warning. The first sentence enumerates filter families without fluff; the second directly addresses a common misuse. It earns its length given the tool's complexity.

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?

Despite lacking an output schema and having 55 parameters, the description provides a strong conceptual overview and key operational details (mood vs vibes, whole-library scope, compound filtering). It doesn't mention pagination or return structure, but those are likely implicit given the filter list. It is adequate for an agent to select and invoke correctly.

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 47%, so the description must compensate. It groups all 55 parameters into meaningful categories (year/date ranges, recency, mood axes, descriptors, vibe membership, tags, duration, time-of-day, diversity caps, affinity ranking). It adds semantic depth by explaining how mood-related filters work differently from vibes, and clarifies max_per_artist usage. This is more than the schema 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?

The description clearly states it is 'The main query tool, over the WHOLE library' with a comprehensive list of filter categories. It distinguishes itself from siblings by emphasizing its primary search role and explicitly contrasting 'vibes' vs 'mood_vibes' to guide usage. This is a specific verb+resource+scope with clear differentiation.

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 explicit guidance for mood requests: 'prefer mood_vibes / moods / the axis ranges over vibes' and explains why, which functions as a when-to-use within the tool. It also establishes itself as the main query tool. However, it does not mention when to use sibling tools like similar_tracks or listening_history, so it lacks full alternative routing.

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