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

Adds value beyond annotations by disclosing cost behavior (consumes no generation quota), which annotations don't cover. Also discloses AND-combination semantics for filters and the commercial-licensing status of results. Doesn't cover pagination behavior, though limit/offset params exist.

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?

Four short sentences, each earning its place: purpose, cost/routing, filter semantics, and licensing. Front-loaded with the core purpose and the most decision-relevant fact (free).

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 needn't be explained. However, with 12 parameters at 8% schema coverage, an agent cannot construct a working query without external documentation. The get_library_filters pointer mitigates value discovery but not query shape, leaving a real gap.

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 only 8% with 12 parameters, so the description must carry significant weight but adds almost nothing: only the AND-combination note and 'all filters combine'. It never explains what bpm, moods, genres, themes, activities, instruments, playlists, duration, mode, or the pagination params accept or how string filters are formatted.

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 (Search) and resource (Mubert's pre-made royalty-free catalogue), and explicitly distinguishes from the generation siblings by noting it's free and should be reached for before generating. An agent can tell it apart from generate_track and get_track without opening a schema.

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?

Explicitly states when to use it ('reach for it before generating whenever an existing track would do') and names the alternative workflow (generating). It also directs the agent to call get_library_filters first, which is concrete sequencing guidance.

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