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

Annotations provide readOnlyHint=true, and the description reinforces this with 'Descriptive, not a recommendation.' It adds meaningful behavioral context beyond the annotation: the free-tier quota (anonymous 5/day, signed-in 10/day, power 50/day), the $0.05 overage cost via x402, and the paging cap of 200. This is exactly the kind of cost/rate-limit context that helps an agent decide whether to call the tool.

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 dense sentence that front-loads the core purpose and metric list, then appends the paging and cost caveats. It is long but every clause earns its place: the metric enumeration is necessary for purpose clarity, and the quota/cost info is necessary for behavioral transparency. Slightly overstuffed, but well-ordered.

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 read-only, paged list tool with a fully documented schema, the description covers the essential context: what metrics are returned, paging behavior, cost/quota, and the source of list_id. There is no output schema, so the description's metric list partially compensates for the lack of a return-value schema. It doesn't describe the exact response shape, but the metric enumeration is sufficient for an agent to know what to expect.

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 description coverage is 100%, so the schema already documents all three parameters (list_id, limit, offset) with descriptions. The tool description adds the context that list_id comes from list_smart_lists and that paging is capped at 200, which slightly enriches the schema. Baseline 3 is appropriate because the schema carries the parameter documentation burden.

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 opens with a specific verb and resource: 'Per-symbol metrics for a stock screen,' then enumerates the exact metric families returned. It distinguishes itself from siblings like get_smart_list (the list itself) and get_smart_list_changes (changes over time) by stating it returns per-symbol metrics. The scope is unambiguous.

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 states the tool is for a stock screen and lists the metrics, which implies when to use it: when you need per-symbol detail for a screen. It also notes paging (max 200 per call) and the list_id source from list_smart_lists, which orients the agent. It does not explicitly name sibling alternatives or state when NOT to use it, but the context is clear enough.

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