vpn-mcp

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden. It discloses prerequisites (vpn_connect required first), output structure (returns status code, headers, and body), and isolation guarantees ('only vpn_fetch requests go through VPN'). Lacks explicit mention of read-only nature, timeouts, or error handling, preventing a perfect score.

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?

Five sentences, each earning its place: purpose, comparative usage, prerequisite, output format, and safety model. Information is front-loaded and there is no redundant text.

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?

Despite no output schema, the description compensates by explicitly stating return values. Given a 4-parameter fetch tool with no annotations, it covers prerequisites, sibling differentiation, output structure, and the VPN tunneling scope completely.

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?

Input schema has 100% description coverage (url, method with default noted, headers, body), so the description appropriately delegates parameter semantics to the schema. The description focuses on behavioral context rather than repeating parameter details, which is correct for complete schemas.

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 uses a specific verb-resource pattern ('Fetch a URL through the VPN tunnel') and explicitly distinguishes from sibling tools by contrasting with 'WebFetch' and stating this is the only request path that goes through VPN, differentiating it from the connection management siblings (vpn_connect, vpn_status, etc.).

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?

Explicitly states when to use vs. alternatives ('Use this instead of WebFetch when you need the request to come from the VPN exit node IP'), prerequisites ('Requires vpn_connect() first'), and relative positioning ('This is the safe default').

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