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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered; the description adds real value by describing the returned fields, the label-to-key naming convention, and the underlying GET endpoint. Pagination behavior is left to the schema rather than the description.

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?

Three short sentences, front-loaded with the content of the response and followed by the key-format tip and endpoint. The endpoint line is mildly redundant with the tool name but not wasteful.

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, the description carries the burden of explaining return values and does so concretely (label, type, allowed values, mandatory). Only the pagination/response envelope isn't described, which is a minor gap for a simple read tool.

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?

Schema coverage is 67%: limit and offset are well documented in the schema, while list_id has no schema description and is only illuminated by the 'GET /lists/{list_id}/fields' template. That is adequate but adds little beyond the structured fields, which fits the baseline for moderate coverage.

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?

It states the resource precisely — the fields (columns) of a contact list — and enumerates what a field record contains (label, type, allowed values, mandatory), so an agent knows exactly what comes back. It doesn't explicitly contrast itself with siblings like vision6_list_lists, though the name and description make the distinction inferable.

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: the note that the lowercase-underscore label is the key used for contact values and filters hints that this tool is a prerequisite for filtering or creating contacts. There is no explicit when-to-use, when-not, or named alternative.

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