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

Annotations already carry readOnly/idempotent/openWorld semantics, so the description's real contribution is the data caveat: counts are lifetime, and 0 means fewer than 1,000 plays — essential for interpreting results correctly. It would score higher if it also noted missing/unknown tracks or response ordering.

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?

Three short sentences, front-loaded with the payload, then the comparative value proposition, then the interpretation caveat. Every sentence earns its place and nothing is redundant.

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 responsibly enumerates the returned fields and explains the zero-value encoding, which is the main gotcha for a single-parameter read tool. Only edge cases (invalid IDs, not-found tracks, result ordering) are left 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% and the schema already specifies accepted formats (IDs, spotify:track URIs, open.spotify.com URLs) and the 1–50 range. The description only restates the 50-track cap, adding no new parameter meaning.

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 ('lifetime Spotify play counts (streams) for up to 50 tracks') plus the returned fields (track name, artists, release date), which is far more concrete than a sibling like get_tracks. It implies but never names the differentiation from get_track_insights or get_tracks, so it stops short of unambiguous routing.

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 fastest way to compare streams' hints at the comparison use case, but no alternative tool is named and there are no exclusions (e.g., when to prefer get_track_insights for per-track analysis). Usage must be inferred by the agent.

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