List servers

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

readOnlyHint=true already establishes the safety profile, and the description adds a genuinely useful behavioral guarantee beyond it: 'Never returns secrets.' It stops short of describing response shape or size, but the security note is the important addition here.

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?

A single sentence, front-loaded with the verb and resource, and the security caveat appended compactly. Nothing is padded and nothing needed is cut.

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?

With zero parameters and no output schema, the description carries the burden of conveying what comes back, and it does so at a useful level (per-account sections plus the fields within them) while flagging the secrets exclusion. A bit more on the return shape would make it fully self-sufficient.

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 tool takes zero parameters, so the baseline of 4 applies. The description's mention of returned fields (hosts, users, auth types) is about output, not inputs, so there is no parameter semantics to document.

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?

States a specific verb ('List') and resource ('configured accounts/servers') and even enumerates the sections returned (mail/calDav/cardDav with hosts, users, auth types). It is clearly distinguishable from every sibling, which are all message/event/contact operations, though it never names an alternative explicitly.

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?

Usage is only implied: an agent infers it should call this to discover configured accounts when setting up or delegating to other tools. No when-to-use or when-not-to-use guidance is given, but no sibling overlaps the same resource, so ambiguity is low.

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