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 of behavioral disclosure. It only states the basic action ('Get detailed information') without covering critical aspects like authentication requirements, rate limits, error handling, or data freshness. This is inadequate for a tool with multiple parameters and potential external dependencies.

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 bullet-like formatting for parameters. It's front-loaded with the core purpose and avoids unnecessary verbosity, though the parameter explanations are somewhat terse.

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, no annotations) and the presence of an output schema, the description is partially complete. It covers parameters well but lacks behavioral context and usage guidelines. The output schema handles return values, so the description's brief 'Returns' statement is sufficient.

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 includes an 'Args' section that lists all six parameters with brief explanations, adding significant value beyond the input schema (which has 0% description coverage). It clarifies purposes like 'mbid' for MusicBrainz ID and 'username for personalized info,' though it could provide more detail on formats or constraints.

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 album.' It specifies the verb ('Get') and resource ('album'), making the intent unambiguous. However, it doesn't explicitly differentiate from sibling tools like 'get_album_top_tags' or 'search_albums,' which prevents a perfect score.

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 sibling tools like 'get_album_top_tags' for tag-specific data or 'search_albums' for discovery, leaving the agent without context for tool selection.

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