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 the full burden of behavioral disclosure. It mentions that the tool returns a 'Formatted list of global top tracks', which gives some insight into output format, but lacks details on permissions, rate limits, data freshness, or error handling. For a read operation with no annotations, this is a significant gap in transparency.

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 appropriately sized and front-loaded, with the purpose stated first, followed by clear sections for 'Args' and 'Returns'. Every sentence earns its place by providing essential information without redundancy, making it easy to scan and understand quickly.

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 that there is an output schema (which handles return values), no annotations, and low schema coverage, the description is moderately complete. It covers the purpose and parameters well but lacks behavioral details like authentication needs or rate limits. For a simple read tool, it's adequate but could be more comprehensive to fully guide an agent.

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 meaningful context beyond the input schema, which has 0% description coverage. It explains that 'limit' is the 'Maximum number of results to return (1-50, default: 10)' and 'page' is the 'Page number to retrieve (default: 1)', including valid ranges and defaults. This compensates well for the schema's lack of descriptions, though it doesn't fully detail all possible behaviors (e.g., pagination limits).

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 global top tracks chart'. It specifies the verb 'Get' and the resource 'global top tracks chart', making it distinct from siblings like 'get_artist_top_tracks' or 'get_user_top_tracks' by emphasizing the global scope. However, it doesn't explicitly differentiate from all siblings, such as 'get_top_artists', which might be similar in structure but for different 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 to choose this over siblings like 'get_artist_top_tracks' (for artist-specific data) or 'get_user_top_tracks' (for user-specific data), nor does it specify any prerequisites or exclusions. The usage is implied by the name and description but not explicitly stated.

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