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

No annotations are provided, so the description carries the full burden. It clearly indicates a read-only listing operation and describes the output content. It doesn't mention pagination or auth, but for a simple list tool this is sufficient and no contradictions exist.

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, front-loaded sentence that wastes no words. It opens with the core action and resource, then lists the additional details returned. Efficient and well-structured.

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 simple list tool with one optional filter parameter and no output schema, the description adequately conveys the purpose and output content. It could explicitly mention the category filter, but the schema already covers that, making the description sufficiently complete.

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 describes the single optional parameter (category) with its enum values and a clear description ('Filter by category'). The tool description adds no extra semantics beyond the schema, but the schema already covers parameter meaning, so baseline 3 is appropriate.

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 action (list) and the resource (supported hosting and email providers), and specifies the content returned (connection methods, target requirements, setup notes). This distinguishes it from sibling list_* tools like list_domains or list_services.

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 use for discovering available providers and their setup details, but does not explicitly state when to use this tool vs alternatives or any exclusion criteria. With many sibling tools, more explicit guidance would be beneficial, but the purpose is clear enough for basic usage.

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