Ludus FastMCP

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 states this is a read operation ('Get information'), which implies it's non-destructive, but doesn't cover other aspects like authentication requirements, rate limits, error conditions, or what 'User information' entails (e.g., fields returned, format). For a tool with zero annotation coverage, this leaves significant gaps in understanding its behavior.

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 core purpose stated first ('Get information about a specific user.'), followed by structured sections for Args and Returns. There's no wasted text, though the Returns section is vague ('User information') and could be more informative if not for the presence of an output schema.

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 low complexity (1 parameter, no nested objects) and the presence of an output schema (which reduces the need to explain return values), the description is minimally adequate. However, it lacks context on usage guidelines and behavioral traits, which are important even for simple tools. With no annotations, it doesn't fully compensate for missing structured data.

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 a parameter section that documents 'user_id: User ID to retrieve', adding meaning beyond the input schema (which has 0% description coverage and only specifies type 'string'). However, it doesn't provide details on the format, constraints, or examples of valid user IDs. With 1 parameter and low schema coverage, this partial compensation results in a baseline score.

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 information about a specific user.' It uses a specific verb ('Get') and resource ('user'), making the intent unambiguous. However, it doesn't explicitly differentiate from sibling tools like 'list_users' or 'get_user_apikey', which would be needed for 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 'list_users' (for listing all users) or 'get_user_apikey' (for retrieving API keys), nor does it specify prerequisites or contexts where this tool is appropriate. The only implied usage is retrieving a single user by ID.

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