Last.fm MCP Server

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

With no annotations provided, the description carries the full burden. It discloses that the tool can personalize data with a username and mentions autocorrection behavior. However, it doesn't cover important aspects like rate limits, authentication requirements (though sibling tools suggest an auth system), error conditions, or response format details. The description adds some behavioral context but leaves significant gaps.

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 a clear opening sentence followed by organized parameter explanations. It's appropriately sized for a 5-parameter tool. Minor improvements could include bolding parameter names or removing the vague 'etc.' but overall it's efficient and front-loaded.

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, no annotations, but with output schema), the description does a good job. It explains all parameters thoroughly and mentions the return value. The output schema existence means it doesn't need to detail return format. However, it could better address authentication context given sibling auth tools.

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 fully compensates by explaining all 5 parameters in detail. It clarifies that artist and mbid are mutually optional, describes lang as an ISO 639 alpha-2 code, explains autocorrect's purpose, and specifies how username personalizes results. 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 an artist by name or MBID.' It specifies the resource (artist) and action (get detailed information), though it doesn't explicitly differentiate from siblings like 'search_artists' or 'get_top_artists.' The mention of personalization with username adds specificity.

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 description provides some usage context: it mentions that either artist name or MBID can be used, and that username provides personalized data. However, it doesn't explicitly state when to use this tool versus alternatives like 'search_artists' or 'get_top_artists,' nor does it mention prerequisites (e.g., authentication needs). The guidance is implied rather than explicit.

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