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 this is a read operation ('returns'), but doesn't mention any behavioral traits such as rate limits, authentication requirements, data freshness, or potential errors. For a tool with zero annotation coverage, 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 a single, efficient sentence that front-loads the key information: what the tool does and what data it returns. There is no wasted verbiage, and every word earns its place by specifying the resource and output details clearly.

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 has no parameters, no output schema, and no annotations, the description provides a basic understanding of purpose but lacks completeness. It doesn't explain the return format (e.g., JSON structure), data units, or any limitations, which could hinder an agent's ability to use the tool effectively without additional context.

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 tool has 0 parameters with 100% schema description coverage, so the schema fully documents the absence of inputs. The description doesn't need to add parameter semantics, and it doesn't contradict the schema. A baseline of 4 is appropriate as the description doesn't have to compensate for any parameter gaps.

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: 'Returns the latest CoinMarketCap 100 Index value, constituents, and constituent weights.' It specifies the verb ('returns') and resource ('CoinMarketCap 100 Index') with details on what data is included. However, it doesn't explicitly differentiate from its sibling 'cmc100IndexHistorical', which provides historical data instead of latest.

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' data, suggesting this tool is for current information rather than historical trends. However, it lacks explicit guidance on when to use this tool versus alternatives like 'cmc100IndexHistorical' or other crypto data tools, leaving the agent to infer the distinction based on the 'latest' keyword.

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