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

Annotations already declare readOnly, idempotent, non-destructive, and open-world, so the lower bar applies; the description still adds real behavior beyond them — newest-first ordering that flips with since, cursor-based paging, and a per-call cost of 0.5 points. Cost and ordering are exactly the kind of traits annotations cannot express.

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 dense sentences, front-loaded with what the stream is before the paging and cost notes; nothing is redundant. The parenthetical '(with since: oldest first)' is terse enough to be momentarily ambiguous, which keeps it short of a 5.

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 7-parameter tool with no output schema, the description covers ordering, paging, and cost but says nothing about the shape of a returned article (fields, how next_cursor appears, whether symbols filtering is OR) or about following up with get_news_article for full text. Adequate for invocation, thin for interpreting results.

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 already 86%, so the baseline is 3; the description earns above that by explaining the two non-obvious params — since inverts the sort order toward oldest-first and is cheaper when nothing is new, and cursor walks to older pages. It adds semantics the schema text does not state.

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 names the resource precisely ('scored news stream behind Market Pulse') and enumerates what each row carries: symbols, value tier, and sentiment. That distinguishes it from a single-article fetch like get_news_article, though the description never states the retrieval verb or explicitly contrasts with that sibling.

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 guidance is operational rather than comparative: 'Use since to fetch only what is new, cursor for older pages' tells the agent how to poll and paginate. It never says when to choose this over get_news_article or the watch/list tools, so selection between siblings is left to inference.

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