CoinMarketCap 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 states the tool returns a value but does not describe the return format (e.g., numeric score, timestamp, metadata), potential rate limits, authentication needs, or error handling. For a tool with zero annotation coverage, this is a significant gap in transparency, scoring a 2.

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, efficient sentence that directly states the tool's function without any unnecessary words. It is front-loaded with the core action and resource, making it highly concise and well-structured, earning a 5.

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 simplicity (0 parameters, no output schema, no annotations), the description adequately covers the basic purpose. However, it lacks details on the return value format and behavioral aspects, which are important for an AI agent to use it correctly. With no output schema, the description should ideally explain what is returned, but it does not, resulting in a minimally viable but incomplete description, scoring a 3.

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 input schema has 0 parameters with 100% coverage, meaning no parameters are documented. The description does not add parameter information, which is appropriate since there are no parameters. According to the rules, 0 parameters results in a baseline score of 4, as no additional semantics are needed.

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 action ('Returns') and the specific resource ('latest CMC Crypto Fear and Greed Index value'), making the purpose immediately understandable. It distinguishes from the sibling tool 'fearAndGreedHistorical' by specifying 'latest' versus historical data, though it doesn't explicitly name the sibling. This is clear but lacks explicit sibling differentiation, warranting a 4.

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 context by specifying 'latest' value, suggesting it's for current data rather than historical trends. However, it does not provide explicit guidance on when to use this tool versus alternatives like 'fearAndGreedHistorical' or other crypto tools, nor does it mention any prerequisites or exclusions. This results in an implied usage scenario, scoring a 3.

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