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

readOnlyHint=true already tells the agent this is a safe, non-mutating call, so the description's main job is to add context beyond that. It adds the field list and the REST endpoint mapping, but says nothing about pagination, ordering, or what an empty result means.

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?

Two compact sentences: the purpose and returned fields come first, the REST endpoint reference trails as supporting detail. Nothing is padded or redundant.

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 no output schema, enumerating the returned fields (id, name, region, status, created_at) is the key thing the description must supply, and it does. Minor gaps remain around result size or pagination behavior, but for a zero-parameter list tool this is close to 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 tool takes zero parameters, so per the baseline there is no parameter semantics to document. The description does not need to compensate for anything here, and the return-field list is a bonus rather than a schema substitute.

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 gives a specific verb and resource ('List your persistent filesystems') and enumerates the returned fields, so an agent knows exactly what it gets back. It distinguishes itself implicitly from the create/delete filesystem siblings by being the read-only enumeration, though it never names an alternative tool.

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 clause 'that can be attached to instances at launch' hints at the use case (call before launching an instance), but there is no explicit when-to-use or when-not-to-use guidance and no reference to sibling tools. Usage is only inferable.

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