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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered structurally. The description adds a genuinely useful behavioral fact not in the annotations: that no Spotify bearer token is required. It stops short of describing pagination or result limits, but the auth disclosure is meaningful added context.

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?

Two compact clauses with the return behavior front-loaded ahead of the usage guidance. No filler sentences; every clause carries information.

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?

An output schema exists so return values need not be explained, the read-only annotations cover the mutation profile, and both parameters are fully described in the schema. The description completes the picture with auth and usage routing; only result scope/count details are absent, which is minor.

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 id and uri are fully documented including that uri accepts an open.spotify.com URL. The description repeats the URI-or-ID notion but adds no syntax or precedence detail beyond the schema, so 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: 'Returns artists related to a Spotify artist URI or ID.' An agent understands the operation, though it does not explicitly contrast with siblings like spotify_artist_albums or spotify_artist_playlists.

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 gives the precondition ('use when you have an artist URI or ID') and points to the fallback action ('search first only if you need to find one'). This routes the agent well, though it names no specific sibling search tool and gives no when-not guidance.

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