APIFold

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 successfully reveals critical ecosystem constraints: the servers are 'free hosted,' 'proxy a REST API,' and require users to 'bring your own API key.' However, it omits details about response format, caching, or rate limiting.

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 consists of two highly efficient sentences. The first front-loads the core deliverable (the 18 specific servers), while the second adds essential context about the REST proxy architecture and API key requirements. No words are wasted.

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 low complexity (zero parameters, no nested objects) and lack of output schema, the description adequately explains what the tool returns (inventory of 18 servers) and their operational model. It could be improved by hinting at the return structure (e.g., array of server objects), but it is sufficiently complete for agent selection.

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?

Per the evaluation rules, tools with zero parameters receive a baseline score of 4. The input schema is an empty object with no parameters to describe, and the description appropriately focuses on the return value rather than non-existent inputs.

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 'List[s] all 18 free hosted APIFold MCP servers' with specific examples (GitHub, Stripe, Slack, etc.). The plural 'servers' and enumeration of all 18 naturally distinguishes it from sibling 'get_server_endpoint' (singular), making the scope unambiguous.

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 this is a discovery/initialization tool ('List all'), but provides no explicit guidance on when to use this versus 'get_server_endpoint' or prerequisites for using the listed servers. The usage context is inferred from the verb 'List' but not stated explicitly.

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