MCP Chess 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 states the tool 'Get[s] the stats' but doesn't clarify what 'stats' includes, whether it's a read-only operation, potential rate limits, authentication needs, or error handling. This leaves significant gaps in understanding the tool's 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 a single, clear sentence with no wasted words: 'Get the stats for a Chess.com player by username.' It's front-loaded and efficiently conveys the core action, making it easy to parse 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 the lack of annotations and output schema, the description is incomplete. It doesn't explain what 'stats' entails, how results are structured, or any behavioral traits like error responses. For a tool with no structured support, more detail is needed to fully guide the 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 minimal semantics beyond the input schema, which has 0% description coverage and only one parameter 'username'. It implies the parameter is a Chess.com username but doesn't specify format, constraints, or examples. With low schema coverage, the description doesn't fully compensate, but it's not misleading, so a baseline score is appropriate.

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 the stats for a Chess.com player by username.' It specifies the verb ('Get'), resource ('stats'), and target ('Chess.com player'), making it easy to understand. However, it doesn't differentiate from its sibling tool 'get_chess_player_profile', which likely serves a similar but distinct purpose, preventing 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, such as its sibling 'get_chess_player_profile'. It mentions the parameter 'username' but doesn't explain prerequisites, error conditions, or specific contexts for usage, leaving the agent with minimal direction.

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