Last.fm MCP Server

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

No annotations are provided, so the description carries full burden. It mentions the return format ('Formatted list of matching artists with their stats'), which adds some behavioral context, but lacks details on authentication needs, rate limits, error handling, or pagination behavior beyond the 'page' parameter. For a search tool with zero annotation coverage, this is insufficient.

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 purpose statement followed by Args and Returns sections. It is appropriately sized with no redundant information, though the formatting could be slightly more streamlined (e.g., integrating defaults into the purpose).

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 (search with pagination), no annotations, and an output schema present, the description is fairly complete. It covers purpose, parameters, and return format, but could benefit from more behavioral details like authentication or error handling to fully compensate for the lack 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?

Schema description coverage is 0%, so the description must compensate. It provides clear semantics for all three parameters: 'query' as 'Artist name or search query', 'limit' with range and default, and 'page' with default. This adds significant meaning beyond the bare schema, though it could specify data types or constraints more explicitly.

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 specific action ('Search for artists on Last.fm by name'), identifies the resource ('artists'), and distinguishes it from sibling tools like 'search_albums' and 'search_tracks' by specifying the artist focus. The verb 'search' is precise and matches the tool name.

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 implies usage when searching for artists by name, but does not explicitly state when to use this tool versus alternatives like 'get_artist_info' or 'get_top_artists'. No guidance is provided on exclusions or prerequisites, leaving the context somewhat vague.

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