Last.fm MCP Server

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

With no annotations provided, the description carries full burden but offers minimal behavioral context. It mentions 'personalized info (playcount, etc.)' for the username parameter, hinting at authentication needs, but doesn't clarify rate limits, error conditions, or what 'formatted detailed track information' entails. The description doesn't contradict any annotations since none 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?

The description is well-structured with clear sections (purpose, Args, Returns) and uses minimal sentences. The Args section efficiently explains each parameter without redundancy. However, the 'Returns' section is vague ('Formatted detailed track information') and could be more specific about output format.

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?

Given the tool's moderate complexity (5 parameters, 2 required) and the presence of an output schema, the description is partially complete. It adequately explains parameters but lacks behavioral context (authentication needs, error handling) and doesn't leverage the output schema to clarify return values. The description should do more to compensate for the absence of annotations.

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?

With 0% schema description coverage, the description compensates well by explaining all 5 parameters in the Args section. It clarifies that 'artist' and 'track' are required, 'mbid' is optional and refers to MusicBrainz ID, 'autocorrect' enables name correction, and 'username' enables personalized data. This adds substantial meaning beyond the bare schema.

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 the tool's purpose: 'Get detailed information about a track' - a specific verb+resource combination. However, it doesn't explicitly differentiate from sibling tools like 'get_similar_tracks' or 'get_track_top_tags', which also retrieve track-related information but with different scopes.

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?

No guidance is provided about when to use this tool versus alternatives. The description doesn't mention sibling tools like 'get_similar_tracks' for related tracks or 'get_track_top_tags' for tag information, nor does it specify prerequisites like authentication requirements for personalized data when using the username parameter.

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