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 for behavioral disclosure. While it mentions the tool returns 'formatted list of user's recent tracks,' it doesn't describe important behavioral aspects: authentication requirements (though sibling tools suggest this is part of an authenticated API), rate limits, whether data is cached, error conditions, or what 'extended data' includes. The description provides basic functional information but lacks operational 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?

The description is well-structured with a clear purpose statement followed by organized parameter documentation. Every sentence serves a purpose: the first states the tool's function, and subsequent lines document parameters and return value. It's appropriately sized for a tool with 6 parameters, though the 'Returns' section is somewhat vague ('formatted list' could be more specific).

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 (6 parameters, 1 required) and the presence of an output schema, the description is minimally adequate. It covers all parameters and the basic return type, but lacks important context: authentication requirements (implied by sibling tools like 'authenticate_user'), rate limiting, error handling, and what 'extended data' entails. The output schema existence reduces the need to detail return format, but operational context is incomplete.

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?

The description adds significant value beyond the input schema, which has 0% description coverage. It explains all 6 parameters with clear semantics: 'user' as username, 'limit' with range and default, 'page' for pagination, timestamp parameters for filtering, and 'extended' for additional data. This fully compensates for the schema's lack of descriptions, though it doesn't explain timestamp format beyond 'Unix timestamp' or what 'extended data' specifically includes.

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 as 'Get a user's recently played tracks' which is a specific verb+resource combination. It distinguishes this from sibling tools like 'get_user_loved_tracks' or 'get_user_top_tracks' by focusing on recency rather than popularity or affection. However, it doesn't explicitly contrast with all similar siblings like 'get_user_info' which might also return track data.

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 no guidance on when to use this tool versus alternatives. It doesn't mention when this tool is appropriate compared to siblings like 'get_user_top_tracks' (for most-played tracks) or 'get_user_loved_tracks' (for favorited tracks). There's no discussion of prerequisites, authentication requirements, or limitations beyond what's in the parameter list.

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