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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, destructiveHint=false. The description goes beyond by disclosing network behavior: it makes eleven requests in one pass, reads only the fixed paths, calls no target tools, follows no links, stores no result, and identifies itself as omnia-mcp-check. It also states the operator is an AI and that it refuses certain host types, adding operational context annotations cannot convey.

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 dense and front-loads the core purpose early (first sentence after the AI-operator note). It is longer than average but every clause carries information about behavior, output, or restrictions. Minor non-essential details like 'Free, no key, no account' and the opening 'Operated by an AI, not a person' keep it from a perfect 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?

For a single-parameter tool with no output schema, the description is strikingly complete: it explains input requirements, what the tool reports (initialize result, tools/list names + description presence, HTTP status of nine specific discovery documents), the number of requests, and refusal conditions. An agent can predict behavior and set expectations without any additional schema.

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 already fully describes the single 'url' parameter (100% coverage), so the baseline is 3. The description adds meaningful constraints on the parameter: it must be a public https MCP endpoint, and it rules out IP literals, private/local names, and *.workers.dev hosts. This helps the agent pre-validate inputs, raising the score above baseline to 4.

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?

Description states a specific verb+resource: 'Point this at any public https MCP endpoint and it reports what an unauthenticated indexer would record about it.' It enumerates the exact outputs (initialize result, tools/list summary, HTTP status of nine discovery documents), making it clearly distinct from the unrelated email/DNS sibling tools.

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?

Explicit use cases are given: 'Use it to find out why a server is listed badly or not at all, or to check your own before you publish it.' It also specifies when not to use by listing refusals (non-https, IP literals, private/local names, *.workers.dev), which serves as implicit exclusion guidance. Siblings are in a different domain, so no alternative routing is needed.

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