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

Annotations already set readOnlyHint=true, and the description does not contradict that. It adds valuable context by clarifying that this is an HTML hub endpoint rather than the protocol endpoint, and describes the returned data structure (publicLinks, itPage, emails). This goes beyond the annotation's simple read-only flag, though it does not discuss side effects or permissions.

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 compact and well-structured with clear demarcations (WHAT, NOT, RETURNS, USE). It packs extensive disambiguation into a few lines without redundancy, and the critical purpose is front-loaded. Every sentence contributes to correcting potential misuse or clarifying scope.

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 complexity—distinguishing from protocol endpoints, locale variations, and output structure—the description is thorough. It covers what it does, what it is not, what it returns, and how to use it. The existence of an output schema reduces the need to detail return values, yet the description still mentions key fields, making it complete for an agent to invoke correctly.

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 schema fully documents the single 'locale' parameter (100% coverage), including its enum, default, and detailed behavior. The description itself does not mention parameters, so it adds no additional semantic value. Baseline 3 is appropriate because the schema already handles parameter semantics.

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 immediately states 'WHAT: HTML hub /mcp-hub' and clarifies that it is not the protocol endpoint, explicitly distinguishing it from the POST endpoint. It also mentions it returns the same machines as get_it plus additional fields, giving a clear, specific purpose that differentiates it from 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?

It says 'USE to cite discovery URLs,' which is a concrete usage scenario. It also provides exclusions like 'Not Italian, NOT the protocol endpoint' and warns about the Smithery listings and GitHub, helping the agent avoid misapplication. However, it does not explicitly state when to prefer this tool over get_it or mention alternatives, so it lacks a complete when-not-to-use section.

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