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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely non-structured context: results are ordered newest-first, paging is cursor-based via nextCursor, the call is free (no credit cost), and it mirrors GET /api/v1/lists. It does not describe page size behavior or what a list object contains, but with annotations carrying the safety profile this is solid.

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 lines, front-loaded with the resource and ordering, then the pagination mechanic, then cost and REST mapping. 'Free.' as a standalone fragment earns its place as a cost signal but makes the text slightly telegraphic rather than prose.

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?

This is a simple two-parameter read tool, but with no output schema the description should say more about what a 'list' is and what nextCursor/page metadata come back. It covers ordering, paging and cost adequately, yet leaves the return shape and the absence of any end-of-pages signal for the agent to discover at runtime.

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 only 50%, so the description must help; it clarifies cursor semantics ('nextCursor of the previous page' sent back as cursor) beyond the schema's own wording. The limit parameter is never mentioned in the description, leaving the caller to infer paging size and the 1-100 bounds from the schema alone. That partial compensation lands at the baseline 3.

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 names the resource precisely ('the lists of the account') and adds ordering ('newest first') and pagination ('page by page'), which lets an agent separate it from get_list (single list) or create_list without opening a schema. The retrieval verb is only implied by the phrasing rather than stated as 'List all...', so it falls just short of a 5.

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 implied rather than stated: it is the account-wide list endpoint and the pagination loop is spelled out ('send nextCursor back as cursor'), which is real operational guidance. However, no sibling is named as an alternative and there is no explicit when-not-to-use case such as preferring a filtered search tool.

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